MMO-Champion has news of a new beta build coming soon! Sometimes having insomnia isn't such a bad thing. I can catch more of these late night updates heh. ;)
So what's new in the latest beta patch? Not much in the way of pet-related stuff, but the placeholder for the MoP CE pet was added. There's still no information on what this companion will be, though. Oh Blizzard. Such a tease hehe. XD
Another possibly significant update can be found in the datamined client strings. Reading the descriptions of some of them seem to hint that a pet battle team of three will require some unlocking through achievements.
So an example and possible scenario for this: you start out with one possible pet on your team. To add a pet in the second slot you'd need to complete a certain achievement, and the same goes for the third slot.
I'm not sure which achievements we would have to complete. It might require winning a battle against a Pet Trainer/Tamer, or it could be as simple as collecting your first wild pet. Since most of the pet achievements are still non-functional (at the time of this writing), we'll have to wait and see what the achievement rewards are at a later date/time.
I don't even know what to make of the "PET_BREED_QUALITY" client strings, and I don't think I want to speculate about them right now. A legendary pet breed? Err... either it's simply one of the pets from one of the legendary weapons or a very, uhm, EXTRAORDINARY offspring from two special pets. Blizzard did mention possibly allowing us to "grow" our own pets on our personal farms in The Valley of the Four Winds, but I haven't heard much news about that since the initial MoP Press Tour. We'll see!