The iPhone (and iPod Touch) are selling like hot scones! And they play games! Problem being, unlike the PSP and DS, there's very little in the way of quality control on Apple's platform. So we get a lot of games.
You could even say we get too many games, because it's been revealed that there are now over 13,000 games on the App Store. 13,000?!?! It's like a gold rush, only there's more money to be had, and people have better teeth.
For reference, in March, there were only 6000 games. What, is somebody feeding these things after midnight?