Hmm, seizure inducing abuse of .GIF textures, as well as increased lag for some old / crappy computers make this difficult. However, with the right precautions, say you're able to opt out of animated textures, this could be implemented. Definitely need a file size limit, and maybe you could limit the amount of .GIF textures allowed, only allow the head to be animated or create a new kind of expensive item for the animated textures. Just spouting out some ideas.
I like this as long as we don't get green lantern sets.