That stable includes apps like Pocket God and Aurora Feint (Danielle Cassley of both Aurora Feint and OpenFeint told us a while back that she was very excited at the prospect of microtransactions with 3.0), and both of those games, as well as others on the service, are planning to include push notifications with "social challenges" -- you'll challenge a friend to complete a certain goal in game, and then get notified when they meet that goal. Look for those new features in an OpenFeint app near you.
And OpenFeint isn't the only service jockeying for developers' attention -- Urban Airship is also making a bid to host push notifications for iPhone game developers. They've landed one of the first push-enabled games, Tap Tap Revenge, and are looking to offer push to more devs, along with in-app purchase support as well. They don't quite have the library together that OpenFeint already does, but their service integrates, they say, in just a matter of hours, and their aim is to make it "brain dead easy" for developers.
The floodgates are open, and we're sure to see more and more companies jump in on hosting plans like this in the future. Prepare to be pushed.