Emulation ON Xbox 360

Is emulation on the Xbox 360 possible through the media center? My other question is, where do you get emulators for the Xbox 360 (SNES, NES, N64)? Do you use computer emulators, original Xbox emulators or what? I searched google and couldn't find anything. I also saw a video of someone playing an emulator on the xbox 360 on youtube and it was posted 2 years ago. They must have made some progress by now and released some good emulators.
Also, I have no idea if that was fake, so if someone could tell me if it was or not, that would be cool. Thanks.

there is one emu that you can use on xbox360.its a nes emu called "nescafe" and you need windows media centre on your pc.basically the 360 and pc have to be connected and you run the emu through windows media centre.