Hmm...since no one has actually played a PSP, it's not really a question to ask which one is better. You can't judge a book by the cover, as the old saying goes. I have to admit, the DS looks incredible, and the dual-screen feature is REALLY nice to have, but I can't really make a final decision until the PSP comes out in March. I chose PSP because the games being developed are more my style, like Metal Gear AC!D. And, Square-Enix announced that they are developing games for the PSP...think about that for a minute. :-P
But yeah, I can't make a final judgement until PSP comes out.