Had heard of that before (then forgot the name) - looking at it now and it seems a little less indie than expected (looking at the games selection) - more a wannabe Steam competitor?
No obvious mentions of leaderboards/achievements/social features on their site, though, seems very much a distribution platform at the moment (although it did take Steam a while to add some of the nicer stuff)
Wondering about how an 'indie online' network could be funded. Really, it has to be open to free games if it's going to take off. I wonder if the system could be some sort of mesh, where developers host a 'node' of the system with enough capacity for their own game(s)? Ideally, it'd be built on easily-hosted technolody, such as PHP/MySQL - but I can't imagine that scaling up well enough to work with 'indie megahits' such as Minecraft?
The API would need a lot of care, too, to avoid buggy games spamming too many requests to the server(s), keeping data compact and throttled. And then we'd need a port of the API to a wide variety of platforms/languages...
If the primary method of browsing achievements/leaderboards/stats was web-based (rather than in-game), maybe it could be ad-supported to some extent?
As for cheating, with a big enough community, it may not be much of an issue? Let the users report suspected cheats with a couple of mouse clicks, and appoint a small community of 'moderators' to deal with them?