Ok I spent the last 2 days tracking down the new hunter pet abilities. What I can say is this...
Scorpid Sting : works good seems it lands every time; however, the little cockroach is slower than molasses in Januray.
Cat Prowl: Fromt what I gater this is a very convienent ability in PVP I reserve my opinion for PVE since I have had problems with it. Most of it was because of conflictions with some of the UI Addon's I use. Damn thing would go stealth as I was runing, very distasteful.
Wolf Howl: This one is a real good attack since it can be used before an attack on the party, adding attack damage.
Bird/Bat Shriek: This one is also decent in combat since it drops attack on every non pc in the area by a significant amount. I did not see the shriek itself as a aggro magnet. I used my bat in close proximity for a few mobs last night and the bat only grabbed aggro on his target but all mobs around him were affected.
Goodintentions has a great animal list now for where all these can be found.