I just downloaded the Mega Man 9 demo on my PS3, and damn, is it good. Whenever I manage to get past the first level, Capcom so has my $10.
Penny Arcade has said it better than I ever could (And this is probably the best endorsement of a video game I have ever seen):
I just had to share my nostalgic joy. If you have a system that will play Mega Man 9, you should get it.