Some of this is a little outdated, but I wanted to cover it now, anway.
In part of WoW moving away for having ranks of various spells, they changed prowl (and rogue stealth) to only be one rank. Prowl will now only have to be trained once, and this will have a 30% speed decrease, at level 20.
Why does this matter? Well, the old ranks of prowl used to be: Rank 1 (learned at level 20) = lowers speed by 40%, Rank 2 (learned at level 40) = 35%, Rank 3 = 30% (learned at level 60). So, in patch 3.3, the change means that there will only be one rank of prowl, and it will always be a 30% speed decrease, trained at level 20. So, prowling around stealthily as a cat while leveling just got a whole lot better!
In mid-November (or somewhere around there), we all have to switch to using battle.net accounts. Some of us have volunteered to switch over, but they are going to make it mandatory next month. Part of the reason for switching to a battle.net login process is so that they can link starcraft & warcraft accounts together for various things, such as cross-game chat improvements. I recommend doing the switch early & not waiting for the last minute to do it.
As a reward for having your battle.net account up and running when the switch-over happens, we all get free penguin pets. Anyone who played in the Beta for WotLK remembers getting a penguin named Mr. Chilly. It turns out that Mr. Chilly’s first name is Oswald, and he’ll be returning as the reward for upgrading your account to battle.net when they do the forced upgrades. If you merge early, you still get the new penguin.
Isn’t he cute? This is something I’m very excited about. I worked really hard to be able to acquire his cousin (Pengu) when I first hit Northrend (I did the dailies every day from the level I could start doing them). So, I’m even more excited to get Mr. Oswald Chilly back very soon!