I was going to wait to post this, but it looks like like GW is already releasing information on the changes in the 7th edition, and I never agreed to any confidentiality clause, so I figure it's ok to go ahead and post it. If they contact me about it I'll probably pull it back down later (if they ask nicely).
At first glance, there doesn't seem to be that many changes between the latest edition of WHFB and the previous one, but when you start to look more closely you find that there are quite a few. Most of them seem to have been made with the goal of eliminating some of the trickier bits in the rules.
Here's a list of the actual changes I've found so far. I probaby missed a few (in fact I'm sure I did after reading some of the stuff already up on the
GW site that mentions changes that I missed), and I may have included one or two "changes" that were actually around in the last edition, and I just missed them. I aplogize for any of those that slipped through.
Unit strengths: warmachines now have a strength equal to their remaining crew rather than just a fixed strength of three.
Characters:
Line of Sight: single characters on foot no longer get a 360 degree arc of sight, but only the 90 degree arc of most units. This may not have been intentional, but is the literal interpretation of the rules as written.
Proximity to Friendly Troops: this rule is gone now, you can always shoot at an independent character that has not joined a unit, but the shot is at -1 if he's human-sized and on foot.
Challenges: some clarifications to the rules and a change with Chariots. Creatures pulling a chariot now fight in a challenge, but other riders still do not.
Look Out Sir: does not apply to characters of unit strength 5+
Characters and Psychology: there are a lot of clarifications as to how characters and units with different psychology rules interact when a character joins a unit.
Terrain:
Edge of the Table: it's now considered impassable unless you are fleeing or pursuing.
Hills: in addition to the second rank of a unit on a hill getting to shoot, anyone shooting
at a unit on a hill can fire with
all ranks since all ranks can see over each other to the elevated target.
Formations:
Rear Ranks: several clarifications on what happens to uneven rear ranks in different situations.
Change Formation: instead of adding or subtracting ranks, you get to move up to 5 or 10 models (depending on how much movement you give up) to or from the front rank, adjusting the remaining ranks accordingly.
Extra Ranks Bonus: you must now have at least 5 models per rank to get the bonus instead of 4, also the note about not applying when attacked in the side is gone. I'm unsure if the effect of it is still implied by other rules.
Close Combat:
Redirecting a Charge: This is now gone and replaced with the Enemy in the Way rule. It basically works the same, but only if the new target is directly in your path. No maneuvering is allowed (except the usual wheel to bring the most units into base contact in a charge).
Cover: this is now defined as applying if half or more of the unit is in cover.
Defended Obstacle: you no longer need 6's to hit units defending an obstacle, instead the attacker loses all charge bonuses, instead fighting as if it was the second round of combat (hence, obstacles provide no bonus after the charge).
Break Test: new rule called Insane Courage now makes double 1's an automatic success in a break test.
Fleeing: units now always flee in a direct line away from their attacker. They do not move around anything. If they hit impassable terrain or an enemy unit of strength 5+ they are destroyed. If they stop on a friendly unit or enemy of strength less than 5 then they are moved beyond that unit and stop there instead. The same rule applies during subsequent turns with the fleeing unit now moving straight towards the nearest table edge.
Pursuit into Fresh Enemy: the target can now choose to flee if it wishes to.
Lapping Around & Expanded Frontage: these are gone now. Instead the winner of a fight may now perform a Change Formation or a Turn maneuver.
Psychology: this section has, interestingly enough, moved from the basic to the advanced section of the rules.
Panic from Fleeing units: units no longer panic due to nearby fleeing units, instead they take a panic test when a friendly unit flees through them.
Panic from destroyed units: this is now caused if the unit is destroyed by any means within 6". There's no longer a difference if the unit was destroyed by shooting instead of close combat, or if the unit destroyed was fleeing. Also, the destroyed unit must be strength 5+ to trigger this test (this appears to be the case for all unit triggered panic tests, including fleeing or breaking units).
Panic from 25% casualties: this is clarified to apply to any damage caused outside of the close combat phase (including such things as goblin fanatics)
Defeated by a Fear Causing Enemy: same as before, but the new Insane Courage rule applies which allows a unit to not break if it rolls double 1's, even if it would otherwise automatically break.
Stupidity: Stupidity now ends whenever a stupid creature enters Close Combat. It's unclear if Stupid creatures are now meant to be subject to all psychology once in Close Combat, but the way it is written they are.
Immune to Psychology & Unbreakable: These two classifications have been added to the Psychology section.
Weapons:
Pistol (hand-to-hand): no longer gets bonus on first turn of Close Combat, simply counts as a hand weapon.
Pistol (shooting): added stats for a brace of pistols (2x multiple shots)
Monsters: a lot of rewriting here, but mostly for clarity. The biggest change is in the Monster Reaction Table for when a rider is slain and the monster fails its Leadership check. Monsters no longer have a chance of fleeing. They always stay and fight, but under three different conditions. The first is that they fight as normal but subject to Stupidity. The second is that they fight as normal but can't move except to turn to face the enemy and become Unbreakable. The third is that they fight as normal but become subject to Frenzy and Hatred for the rest of the game. There's also a rule added for what happens if a rider has his mount killed as the result of a Stand and Shoot reaction to a charge.
Chariots:
High Strength Hits on Chariots: chariots now get to check their armour save, if any, before being destoyed by a Strength 7 or greater hit.
Impact Hits: these are now distributed in the same way as shooting hits.
Fleeing Chariots: chariots do impact hits against any unit they flee through, friend or foe. If they are forced to flee through an enemy unit of Strength 5+ they still do impact hits before being removed.
Skirmishers:
Double Pace: Skirmishers no longer have this rule. They are now under the same March restrictions as everyone else in regards to proximity to the enemy.
Battle Standard:
Combat Bonus: battle standards now add with unit standards if both are in the same unit.
Capturing: capturing a Battle Standard is clarified.
War Machines:
Movement: war machines and their crew now move as skirmishers (they more or less did before by default, but this is now clearly stated). The movement rate of a war machine is reduced if crew members are killed by the percentage of crew killed.
Characters: a character that joins a war machine can still shoot independently with his own weapons.
Loss of Crew: this is now a standard rule for all war machines, rather than defined for each one separately. Any machine with a crew of 3+ to start with fires normally until down to 1 crewmember, at which point it can only fire every other turn. A machine that only has 2 crew to begin with continues to fire normally if a crew member is lost.
Fleeing: an attacker no longer has the option to bypass a war machine to pursue the fleeing crew, the attacker must stop at the war machine.
Fleeing Crew: crew are treated as a skirmishing unit until they recrew a weapon. Crews no longer automatically flee if charged when not crewing a machine, and can fight in close combat normally as a skirmishing unit.
Close Combat: the rules allow for machines to be attacked in close combat. If it happens they are hit automatically. If there is no crew left they are automatically destroyed. An attacking unit is now allowed to pursue broken crew or overrun after destroying a war machine. A victorious war machine crew does not need to make a test if they choose not to pursue a broken unit.
Cannon:
Which models are hit: there are several clarifications made.
Grapshot: now uses the flame template and causes hits with a strength equal to the roll of an artillery die with a -1 armor save modifier.
Special Rules: several special rules that appear in multiple army lists are now listed in the main rule book as well.
Buildings: it appears that this is one section that has been completely redone. I'm not going to list all the changes here.
Special Features: a new section covering special terrain features, the control of which gives you bonus VP or special abilities in the game.
Victory Points:
Enemy Units at Half Strength: the VP are gained when a unit falls to half strength rather than below half strength as before.
Victory Chart: this has been redone to make for more breakdowns at the small end and fewer at the large end. The result appears to be the same for games of 1000-1499 and 2000-4999 points. Games of 1500 to 1999 will end up with a draw being more likely and games of 999 or less and 5000 or more will end up with a draw being less likely.
Magic:
Power Dice: extra dice from a Wizard's level are no longer put into the Power Pool, instead they can only be used by the Wizard that generates them. Any other dice from items or other sources, including the 2 basic dice, are put in the pool as before.
Miscast Table: this has been completely rewritten. In most cases the results are more damaging for the caster.
Remains In Play: There are clarifications on how this works with characters joining and leaving units when one or the other are under the effects of a spell.
Selecting Spells: the new example seems to indicate that you can choose to substitute the first spell on the list for any other spell a wizard rolls after the wizard rolls for all of them. This may have been the intention all along, but it wasn't clear from the old example.
Spell lists: lots of tweaks to casting costs, and a few real changes. Bane of Forged Steel, Storm of Cronos, Blinding Light, Father of the Thorn, and Death Dealer are all replaced by new spells. Portent of Far replaces Second Sign of Amul as the default spell in the Heavens list, and Burning Gaze replaces Pha's Illumination as the default spell in the Light list. Overall, Heavens has been nerfed while the weaker lists appear to have been buffed or at least given "fluffier" spells (for example the new Life spell is a healing spell).
Magic Items:
Fleeing: magic items that require "activation" can't be used by fleeing units (this is defined in the rules).
Dispel Scrolls: using one no longer cancels a Remains In Play spell cast by the user. It's now clarified that it must be used at the time the spell to be dispelled is cast and not later.