Shortly before Microsoft's press conference was set to kick off E3 2008, Nintendo announced Wii MotionPlus, an accessory that allows the Wii Remote to recognize 3-D space.
The Wii Motion Plus snaps into the bottom of the Wii Remote and provides a 1:1 response in the controller's motion control. What this means in practical terms is that the Remote will now recognize not only movement, but height and relative orientation, allowing far more precise control.
Nintendo offered no further information about the MotionPlus, presumably saving information about games and the like for its own press conference tomorrow morning. Given the widely-held belief that Microsoft was planning to announce a motion-sensitive 360 controller during its press conference, Nintendo's early announcement seems like a blatant attempt to steal the show.