That's actually a really good idea. I'm envisioning Macbook Pros with touchpads that are seamlessly integrated into the laptop body, spanning the entire width just below the keyboard. You could use two hands and it'd almost have iPad functionality.

Edit: Actually, it looks like this is almost what the MagicTrackpad is, just not quite as wide as it could be. http://www.apple.com/magictrackpad/