Here's the problem though...
The DS has superior developed games.
What the PSP has over the DS currently is Homebrew. Don't poke the Flashcarts at us. You can't stick a flashcart into a computer and code there. You can't bring anything onto a DS using a flashcart. You can stick an SD into any computer. Much like you can stick a Memory Stick into any computer.
I don't like the DSi, and I won't be getting it. Still, the opportunities that it presents for legitimate independent coders to experiment with the dual screens is exciting.