First off, I own an iPhone so I can speak with some ethos to this topic.
But, before you call me a fanboy or label me biased, read on....
To be quite frank, Carmack is speaking out of his ass. As stated earlier, Carmack has generally dealt with x86 (PC) computers. He has little experience with game-console platform (GCP), so rating the iPhones performance compared to a GCP is very inaccurate and rather ill-informed. I imagine Carmack's statements extended from two possible influences:
1. He was directly comparing the hardware specs of each cited GCP to the iPhone's specs.
2. He was trying to gain support from Apple to establish future gaming business endeavors. (Sucking their dicks)
The hardware of each platform cannot be directly compared, primarily due to the unique architecture of each system. It would be quite amateur-ish to simply compare such specifications without comparing raw graphics power in depth (Polygons per second, lighting, texture, and resolution).
There is no way that the graphics capabilities of the iPhone compare to that of the PS2 or XBOX. However, do to recent advancements in technology architecture and Software Development Kits. I imagine that the iPhone contains 4th Generation (PS2 XBOX) lighting and 2D texture imaging. Also, I would hardly say the iPhone is as powerful as the NDS and the PSP COMBINED. It can definitely push more than the NDS but when it comes to the PSP, its a smidge behind the power curve. The PSP utilizes an independent GPU whereas the iPhone relies on integrated graphics technology. The technology intrinsically in the iPhone is superior all of the stated platforms above. However, it was not intended to be a primary gaming device. The PC driven applications on the iPhone such as Safari and Youtube are way beyond what the other stated platforms are capable of. If you want to play video games, get a PSP. If you want a superior and versatile handheld device get an iPhone. The lack of physical buttons hinders it far more as a gaming device than its graphics do...
Tim Y.
