With 4.01 actively being deployed to my pc at this moment, I thought I'd like to point out, you are all beta users. OK, sure, it's been tested in the PTR, but there go your addons (or here) Time to start re-testing. Oh, and that spell rotation, forgetaboutit. Warlocks, do we even get soulburn? Guess have to check the trainers..
To reinforce this point, Blizzard has published the beta test realm patch notes as part of the loader we are all getting.. Not even the most recent patch notes (see patch version at top of page).