General Rulebook FAQ
First off they've clarified the rules for Look Out Sir which should make things a bit more straightforward. Crucially it's now the closest model to the character that takes the wound instead of any within 6". This will change the way the wounds are allocated in a big way.
Vehicles now lose a hull point if they immobilise on difficult terrain. Seems a bit daft to me but whatever. They've clarified that fliers move 18" at Combat Speed and UP TO 36" at Cruising Speed. Makes sense and should stop those people who thought it was 18" or 36". It also moves the exact number of inches it moved if it suffers locked velocity (so keep an eye on your opponent!).
Paladins, Wolf Guard, Crisis Shas'vre and Nobs are no longer characters! This will really upset people who were planning all sorts of wound allocation shenanigans. However, when leading a unit these guys are still characters. Bit of a shame for nob bikers but for everything else it makes sense.
As we thought nothing can modify snap shots to anything but BS1. The Death Ray can't hit flyers which is what I was saying all along but got shouted down for!
You can now tarpit dreads again with units that can't possibly hurt it. They've clarified that power fists Pile In at I1 and not at the model's base initiative. Feel No Pain weirdly works against Perils of the Warp even though an invulnerable save doesn't!
If your vehicle blows up in the enemy turn you can't then charge out of it in your turn (unless it's an assault vehicle). Bit frustrating since it's already difficult enough to charge from a vehicle. Flyers with locked velocity can't switch to hover mode.
Aegis lines must now be deployed in a single unbroken chain so no sneaky deployments across the entire field. If you've got a load of flyers in reserve and the rest of your army dies then you lose!
The flakk missile thing has been clarified - you only get them if it says so in the codex! We all knew that though right? You can't use reserve modifiers on your allies i.e. no using an astropath to help your stormraven come on (looking at you Matt!).
Sadly you have to pick to either use a runic weapon cancel or a deny the witch. You can't have your cake and eat it! Finally, you have to swap all or none of your psychic powers. No keeping Jaws and picking a Divination power :(
Space Wolves FAQ
An independent character that joins a wolf scouts unit can Outflank. Is it just me who's thinking of attaching a thunderlord? Logan can now pick between Frost Blade and power fist so he get's his I5 again. Everything else isn't very exciting except....
Here's the biggy - wolf standards allow re-roll to hit and wound for Overwatch! For 10 points why wouldn't you take one??
Markerlights can ground flying monstrous creatures. Disruption Pods now give Shrouded but still aren't worth bothering with in my opinion. Basically it means you still get a 5+ save if you don't move. Drones aren't characters like people thought. Markerlights don't work for snap shots. Nothing else exciting except.....
The big deal here is that TARGET LOCKS ARE BACK!! With the combination of Night Vision and splitting fire Tau are going to be awesome!
Dark Eldar FAQ
Klaives are now AP2. Still can't see me taking Incubi though. Pain tokens are no longer instantly effective but instead apply from the end of the phase. Bit of a shame and don't see why they've done that. You can also use Enhanced Aethersails AND go flat out! Now that's fast!
The big deal for me here is that bladevanes are now done by random allocation rather than directional. Shame they didn't make them like the daemons screamers attacks :(
So there we have it. A few interesting changes and a few things that were pretty obvious to most people but needed clarifying to stop the asshats. Here's hoping GW release FAQs more regularly in 6th edition.