iPhone a threat to DS, PSP and Zune?

The portable gaming market has long been ruled by Nintendo. Since the days of the original GameBoy, no one has even come close to what the big N is offering. That’s not to say they haven’t tried, though, because almost every major gaming company out there has come out with a portable to try to knock Nintendo out of the driver’s seat. Can we expect to see something like that from Apple as well?
N’Gai Croal, columnist with Newsweek, has written up a list, iPod playlist style, that the iPhone could cause trouble for. Really, though, how far are we away from Apple integrating gaming into their line? The iPhone brings it just one step closer. Croal, in his article, lists all three current platforms, though all for different reasons. He cites the PSP for digital entertainment, the Zune (which has just announced a gaming focus) for MP3 playing and the DS because, hey, eventually someone’s going to put games on this thing.
Will Apple try to move into the gaming market? It would make sense with how popular they have become with all other handhelds. I wouldn’t be too surprised if they take a shot at it within the next few years.