RIM introduced a slick new feature in BBM 6.1 that was just released. It allows you to have animated BBM avatars (aka profile pictures). These avatars are GIF files but they need to follow certain specs. There is actually a solid source of animated BBM avatars courtesy of some hardcore BBM users.
Check out their gallery at www.bbm-animated.com or let us know where you found your avatars! Of course using Google to find would also yield a significant amount of results 😉