GliGli released a libXenon a Nintendo64 emulator for the homebrew 360. From the Readme/NFO:
Mupen64-360 is a Nintendo64 emulator for the Xbox 360, it's powered by libxenon and it's a port of Wii64 (which itself was a port of Mupen64).
v0.96 Beta: First binary release
Wii64 / Mupen64 teams (guess why :)
GliGli (Xbox 360 port)
Ced2911 (GUI library)
Everyone that contributed to libxenon...