Wow, that really is cool. Mecanum wheels are always great.
@nighterfighter: There are ways to interface NI hardware/software with the Wii, a couple of people have done it. Most notably this guy:
http://decibel.ni.com/content/docs/DOC-2326
The Wii sends out a Bluetooth signal, so if you can sense that and figure it out, you're good to go. I'm sure there's a whole slew of resources out there for people who want to do so.