European Court ruling
from last year. I know Valve currently has no intention of allowing Steam games to be resold, but it might be more difficult for Microsoft to change to such a policy, at least in the Eurozone.
Personally though, I don't care. The only used game I have ever bought was the second Zone of the Enders, and only because it was an older game with a limited run and was already out of production. I would however like to see at least some time limit to such restrictions. It would be pretty lame if, for example, some kid born today couldn't buy an old copy of Halo n
in 15 years' time because he just wasn't born soon enough. Yeah they'll certainly repackage and resell games, but they likely won't for everything and it won't really be the same experience.