We looked at doing this at Kongregate - to us achievements are only meaningful in the context of a community, something you don't get with a distributed system. While the integration with Twitter and Facebook addresses this to some extent, I don't really think it gets at what achievements are all about. They're meaningful to a community of other people who play the game, not to everyone you know on the internet.

Another problem with this is that the other portals that the game would be distributed on are our competitors. They're not really going to take kindly to having our achievements on their site. And frankly, they're not going to want HeyZap's, either.