As indicated by the forum admin/owner Ed Krassenstein, the OUYA will launch with emulations of the good ol’ NES, SNES and Nintendo 64 consoles. EMUya, the NES emulator, has already been submitted for review and should launch with the console itself. The SuperGNES (SNES emulator) will also be available at launch, as well as the Mupen64Plus (Nintendo 64 emulator).
There will probably be more emulators ported for the OUYA in the future. We are already aware of an N-Gage emulation port being developed for the console. It is also notable that obtaining the actual video game ROMs can be illegal, yet it is legal to produce and run the emulators themselves. It is also legal to run a game in emulation if you own a copy of the game’s copyrighted content. The OUYA console is set to launch on March 28th.