Two things that never really happened with any level of success was an Apple video game console and mainstream gaming on the Mac that was as popular as on the Windows PC. Despite this, the iPhone and the app store itself, has brought gaming full speed ahead to the masses thanks to the ease of adoption.
While it might be true that today’s iPhone is simply no match for the complexity of the DS or PSP, give it a couple of years and I definitely see this changing. Not because the graphics or game play will be better. Rather the means of game delivery and the fact that the games are approachable by NON-GAMERS will deliver a huge blow to much of the portable gaming industry I believe.
All of this said, the Wii, XBox and PS3 have nothing to worry about. As dedicated consoles, they are in a league all of their own. No single mobile phone is likely going to come along and change the rules of gaming that much I suspect. In five years time, perhaps. But even that would likely be a stretch.