The MoP Beta will hopefully be starting soon! Possibly mid-month? According to MMO-Champion Blizzard's MoP press tour (March 19th) will lift the NDA and afterwards it's likely that the beta will be playable. How soon after is still unknown.
I'm really excited to check out Pet Battles and see what new "wild pets" they have so far. I wonder how capturing the wild ones will work.
The "account wide" pets thing is also something that I'm going to be checking out. Blizzard mentioned the ability to rename vanity pets, but I have my doubts about that being a priority for developers. I think it would be a fairly nice touch and something that many would enjoy, but if Blizzard's serious about Pet Battles, I can understand that their resources need to go into perfecting that feature first.
I expect a lot of bugs and limited access to stuff, but at least we'll get at taste of what's to come. Then I can formulate a more concrete opinion of the future of pet collecting. Hope for the best, prepare for the worst? We'll see.
There will probably be so much information to take in that I'll probably be making daily posts as I play through the beta. I can't wait! :D