A rumor in Game Informer (full text from GI after the break) states that Gamerscores and achievements will be transferable to Microsoft's next console. As far a rumors go, this is one many Xbox 360 owners might pray Microsoft wouldn't prevent from becoming a reality.
Achievements and Gamerscores are two features of the Xbox 360 that have developed a strong following, particularly among "ch33vo-holics." We can already imagine the internet
"We've also heard that Microsoft is already putting into place its philosophy for the new console, and one thing that will definitely be included is letting existing Xbox 360 gamers migrate their Gamertag over to the new system. Your achievements would also transfer onto the new system instead of having you start from scratch. Loose talk has also heard that Microsoft is already approaching developers about the new system." -- Game Informer (June '08)
[Thanks to Matt at GI for the actual text]