Ok, I stopped by Best Buy and picked up a 2gb microSD card yesterday and finally got to use this thing. First thing I noticed, it can hold a crap load of stuff. I plugged the microSD into my computer, copied the files over, popped it into my DS and it worked like a charm. This is the only way to own a DS, that's for sure. Apparently you can put music and movies on as well, but I haven't tried that out yet. Very cool though, definitely worth the $25 bucks or whatever it was.
So can you load plain old ROMs from the internet on there and play?