During the 24th annual Chaos Communication Congress a fully hacked Nintendo Wii was demoed. The unit opens up the possibility of running home made games with full hardware capabilities on the console. If I recall correctly Nintendo is planning on releasing a SDK for the Nintendo Wii in the near future for people to make their own custom games and make them available on the WiiWare Channel. Here is a snip from the report.
The guys over at 24C3 just demoed a Wii hack that is set to provide native wii homebrew in the near future (not running in GC mode, and with full access to all the Wii hardware!)
They were able to find encryption and decryption keys by doing full memory dumps at runtime over a custom serial interface.
Using these keys, they were able to create a Wii ‘game’ that ran their own code (their demo happened to show live sensor/Wiimote information, amongst a few other things).
There was a video of the announcement on youtube but Google appears to have removed it.