I really doubt any pets will be revealed as anigmagi. Rowling already pulled that stunt once, and it'd be stupid to pull it again, much less this late in the series.

One of the things I'm most concerned about is how Voldemort's wand came to be in Wormtail's possession. The wand must have been removed from the ruins of Godric's Hollow before Harry was found. Hagrid may be in enough of a frenzy to overlook it, but Sirius Black would not miss such an important item. Does this mean that Wormtail was present when Voldemort attacked? If not, to whom might he have revealed the location?

There's a couple theories out there suggesting that Wormtail has had Voldemort's wand all this time (or at least had hidden it while impersonating a pet rat) and that it is the wand he used to blow up the street when Sirius cornered him. Everyone always talks about what a pitiful wizard Wormtail is, but I imagine even an idiot might be able to do some damage with the wand of the most powerful wizard of the age. He can wield Voldemort's wand. He used it to cast the killing curse on Cedric before restoring Voldemort. Crouch, Jr. said that the killing curse takes a strong bit of magic, something Wormtail might not have been able to achieve without a wand that had already cast it so many times.

Of course, the fault is that when Priori Incantatem occured when Harry dueled Voldemort, no spell that might have been used to blow up a street was echoed before Harry's parents appeared.