The ITC (International Trade Commission) has announced that it'll be conducting a probe into the allegations of one Hillcrest Laboratories. Back near the tail end of August, Hillcrest filed a patent infringement suit against Nintendo concerning the motion-sensing aspects of the console. This current report states that Hillcrest claims Nintendo infringed upon 4 different patents. The exact specifics, beyond that, aren't known.
In the worst case scenario, the ITC could ban the Wii from the United States. The last time Nintendo lost a patent infringement suit, they paid $21 million. With the 4 violations, they may win some, they may lose some. If they lose this case, we'd say they're putting up a lot more dough than $21 million, though. Or really smart for not sending us all the Wii stock.