For those still wondering what these are, take a look here and half way down there are pictures of both of the hand helds.
http://www.nintendospin.com/article776.html
I think both have their good and bad points. The PSP obviously has sharper graphics and is the more powerful system, however you cant really compare as Nintendo have now gone a different route where they are saying graphics have now levelled out and the new challenge is different ways to interact with gameplay....and this is where comes in their dual screen, built in microphone and touch screen interactive control system.
E3 (The Electronic Entertainment Expo) is on in the next coming weeks this month so we will probably see some new ways these two consoles will be exploited and hopefully find out some info on the Nintendo Revolution and other next gen consoles too.