Just FYI, the NDS will only emulate stuff via homebrew, and even then it's only NES/GBC support (SNES exists, but is super slow and not very good).
That being said, I have a fair amount of good NDS homebrew -- before I got my iTouch, I could chat on IRC and surf the web with it.
In any case, I'm looking forward to a new handheld -- the DSi wasn't really much of an upgrade over the Lite. If Nintendo really wants to compete against my ipod though, they'd better include a damn good browser and online support system with it. Otherwise I think the NDS may be my last portable Nintendo console for a while.