I just came across this, and I've got to say that I'm impressed by the video. By combining Mario, Megaman, Sonic, and other classic game universes, it looks like they're creating the ultimate 2d platformer.
If they put this on WiiWare, or even a retail game, I would definitely buy it. Currently, I think it's a free project. I'm going to download the beta later today.
Oh. My. Goodness. It also has Doom levels. (even if it's an outdated video)