Animating is one of the many things that Pyglet makes it easy to do. Just recently Erik drew a fabulous sprite sequence for the cell, and I spent some time today integrating it into our game.
My next plan in terms of animation is to make animations seamlessly integrate into anything that calls for a texture. If I make a wrapper class around Texture, and then have the actual texture itself be hidden within a property, I can selectively return the correct texture whenever an object tries to draw. Most things don't need to animate, though, so that's not a really high-priority task.