is it possible to make an animated splash? such as using a .gif?

Yes. Two different ways in fact.

The way that uses a video clip, and modified loginscreen.xml or modified startup.xml

And the kind that uses a modified startup.xml and multiple images

I prefer the first one cause you don't have to take the time to try and sync up a startup.wav if you want a sound to go wiht it like you do the second, you also can just press b to stop it if you don't feel like watching it. They are both fullscreen as well.

This is not exactely a MC360 question so I would imagine this topic won't last very long.