After IGN previewed Unleashed a couple of days ago, it's now GameSpot's turn to preview the upcoming expansion. They've posted an article (rather short compared to IGN's one), but it does give some new information:

"Though the pets are certainly not the only new feature of The Sims: Unleashed, they're a big part of it. Now, your sims can make their way to their local pet store, where they can pick out their very own pet, including about a dozen different breeds of dogs or cats, as well as parrots, fish, and various birds and reptiles. Pets can be named, and once bought, they're treated as part of the family. In the case of dogs and cats, these animals have their very own statistics and skills for you to keep track of."

So pets can indeed be named. It also tells us a bit more about the personality of the pets. There are a few other interesting points in there, but still the IGN article is the most interesting so far. If you want to read the GameSpot article anyhow - including 5 screenshots - go here. Interesting too: a box-shot has appeared at EBGames in the pre-order page: