MMO Champion has dug up a few more animations for the already popular Perky Pug pet, which you will be able to obtain in patch 3.3 by running pickup groups with random players (the current guess on the pet is running with 100 random players, but of course we won't know for sure until it appears on the live realms). The first few animations in this video just look like the Pug has been tweaked a bit (looks to me like that weird leg thing got fixed), but the last animation is definitely new. MMOC suggests you might not want the pet any more after you see it doing this, but I guess Blizzard wanted to go for realism.
Personally, I'm still going for it. Dogs are dogs, and I'm going to be running with the new LFG system (actually, according to the last patch notes, it's called the "Dungeon Finder system" now) anyway, so I might as well go all out and get a vanity pet and the "Patient" title along with all of the other good stuff you usually get from running a ton of heroics. Perky Pug, here I come!
Patch 3.3 is the last major patch of Wrath of the Lich King. With the new Icecrown Citadel 5-man dungeons and 10/25-man raid arriving soon, patch 3.3 will deal the final blow to Arthas. WoW.com's Guide to Patch 3.3 will keep you updated with all the latest patch news.