It has been a awhile but Microsoft said they were looking into those that had artificially inflated their gamerscore by cheating.  Often these people used game saves to get credit for achievements they never earned.  This led to some crazy high gamerscores out there and made is hard to tell who was legit and who was cheating the system.

Well today Microsoft made things right by resetting all the gamerscores for the folks caught cheating.  Adding to the embarrassment, for everyone caught cheating their moto is now, "I'm a dirty Cheater" and to see what this looks like on Xbox.com click here.  I'm glad to say no one on my friends list was affected by this clean sweep.  So far the reaction from the community has been positive but I'm sure this is going to really piss off a few hardcore xbox fans.

Source:
majornelson - gamerscore-correction
gamerscoreblog (Xbox PR Blog)