@ Sky Render
Look a PS3 you won't take with you while travelling from A to B and there are much different expectations.
For the PS3 I expect excellent HDTV graphics and good surround audio, for our two Nintendo DS handhelds I am already satisified with 80's style 2D graphics combined with stereo sound. More important than sucking me into the game experience (actually I wouldn't want this to happen too much, as for instance thiefts could easily take advantage of such a situation) and dazzling me with awesomeness are actually factors like battery life and form factor!
The PSP is very highly specced for a handheld game system (similar to the PS2!) that's why it makes sense to port over PS2-style games onto the platform.
Many Amiga and arcade classics from the distant past are making their way onto the Nintendo DS as well.