Update: It's real. Check out these movies on Wii Fanboy. Thanks, FidoDido1980.
A "source" has just shunted in the direction of Wii jOG, a motion-sensing controller that mirrors your steps on-screen.
As you can see from this Play.com page:
Wii jOG is the innovative motion-sensing controller that brings a whole new dimension to your living room gaming experience. With jOG your character only moves when you do. Plug jOG into your existing console and wow! jOG measures the steps you take and translates them to movement on screen! Now, when you move in the real-world, you really move in the game!
Aside from this listing we have no other details right now, More later this week, hopefully.