Looks like the Plus+ network and Open Feint are going to be made redundant. Apple announced some new features for the 4.0 firmware that includes multitasking, folders, iBooks, and Game Center. Like Xbox Live, Game Center will have achievements, leaderboards and matchmaking.
The catch is, you need to have a 3GS phone, latest iPod Touch, or iPad for the multitasking to work. I’m not sure yet if Game Center will run on every model, but if Plus+/Open Feint games manage to pull it off, I see no reason why Apple can’t. Somewhat disappointing for most of us, and exciting for only a few, OS 4.0 will release somewhere between June and August.