Sometimes your friend finds a fancy animated gif off the web, and he assigns that as his profile picture in iChat. But you can't see the animation, rather the picture remains static. Here's an easy way to see the animated version:
1. Open iChat
2. Open iChat preferences from menu (or press command and , together)
3. Go to "General" tab
4. Select the checkbox against "Animate buddy pictures".
You can now see the animation in your buddy pictures!