Up until this point, the 360 avatars have been dressed in their launch clothing, plus a few additions such as the winter fun pack of avatar coats and gloves. So the idea of being able to play a game on your console, unlock an achievement, and then get a wearable piece of avatar clothing to show off to your friends (especially if it's related to the game at hand) is a really nice touch.
Rare hasn't released any more details on who they're working with or what games this function would be available on, but it's a nice look into the future for what achievements may hold in online settings.
