I've been using Google Wave for about 2 months now and while the original hype has passed I've seen one major advantage it has when it comes to gaming. The open structure and plugin support for dice rollers, character sheets, and combat trackers make it a must for gaming groups that can't meet physically and don't have the online tools that have been developed for some RPGs (best example being D&D 4th).
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Jovian Motto:
Your mind is original. Preserve it.
Your body is a temple. Maintain it.
Immortality is an illusion. Forget it.