I had a conversation with someone within the Xbox team not too long ago, and what I can offer from that conversation is that Microsoft will be doing something along the lines of an Xbox social network.
Achievements will be scalable as well. Meaning an achievement will have different values based the skill level you play. Play it on an easy skill level and you'll get fewer Gamerscore. Play it on hard and you'll get more. You won't necessarily have achievements that only are available on the most difficult level, instead if you want to get the maximum Gamerscore you'll need to play on the hardest level for an achievement. Don't know if that means you can get all the achievements on the easiest level, Then later on a higher level, or if you only earn them on one level.







