Pestilence (Source Re: Pestilence: replace with Blood Boil?)
We're starting to think that the ship has just sailed on Pestilence. As I said, our original intent was that Blood Boil be the main AE attack, but now we're considering making Blood Boil more for tanking, letting Frost use Howling Blast and letting Unholy use Pestilence, because, you know, diseases.

That is a really great idea. Have you given any thought as to how you would implement it? Like would Unholy be the only spec that could spread full strenght diseases?
Something like that. Full strength might be too powerful, but we'll see. Unholy still has a few too many talents like Improved Icy Touch and Corrupting Strikes, so this might be a good replacement (though likely deeper than those two examples). 

Paladin
Retribution Mastery (Source Re: Ret's Mastery)
We have actually changed Retribution's mastery. Having both it and Inquisition boost Holy damage was giving too much power to things like Exorcism (over which you have very little control) and not enough to things like Templar's Verdict (which is supposed to be the centerpiece of your rotation). The new mastery will emphasize Templar's Verdict more. 

Warlock
Warlock Pets (Source Re: Felguard has Bladestorm/MS in latest buil)
While we generally still want to adhere to the goal of Felhunter = Affliction, Felguard = Demo, Imp = Destro, we want everyone to use their other demons sometimes too. That involved making a lot of changes.

For starters, their damage and survivability will move closer together. We want the decision to be more about utility of their abilities than dps or squishiness. Under the new scaling model, the Imp and Succubus have health, mana and armor not too far off from the Felhunter.

We tried out the Imp doing friendly damage when he dispelled because we thought it was interesting for the demonic feel, but we have already removed it. We also tried an ability to knock allies out of CC that break on damage, but we now think that would be too powerful. Currently the Imp still does a dispel on allies.

We wanted to split Devour Magic into offensive and defensive components or else we felt like the Felhunter would always be the obvious choice for PvP. Now you can choose between having an off-the-GCD silence / interrupt and an offensive dispel / purge -or- having a defensive dispel, increases health and an escape tool.

Like everything else in beta, these are subject to change. We're close to being able to get more max-level PvP feedback and will buff or nerf abilities accordingly.