Fours years later, we have a trailer
In 2010, Anthony Burch explained why SpyParty, though "two years away from release," was pretty rad. Four years later and a lot of that prototype art is still in SpyParty's first trailer, though it also shows one of the final character models, which looks lovely. You can see more of the super pretty, animated character models here and an overhauled environment here. The final art is still being integrated into the game.
Yes, SpyParty continues to be a long time coming, but it's such an awesome idea. As the trailer explains. the Spy's goal is to blend in with the party AI while accomplishing various, nefarious tasks. Conversely, the Sniper player has to watch the party from afar and figure out which attendee is the spy player and take them out.
If you want to get into the beta, you can do so through the SpyParty website.