Did anyone read the tweet? (Score 5, Informative)

Posted here in full:

"Low level APIs will allow the Sony NGP to perform about a generation beyond smart phones with comparable specs."

Carmack isn't saying that the hardware in the NGP is a generation ahead of smart phones. He's saying that because of the APIs available to developers they'll be able to utilise that hardware more effectively (specifically that a developer will be able to squeeze an extra generation's worth of performance out of hardware with approx. the same specifications), which makes sense once you consider that the games are pretty much running on the bare metal, and that the entire system is optimised for gaming.