When Steve Jobs introduced the new unibody MacBooks and MacBook Pros at Apple's media event last October, he announced the new glass trackpad with two four finger gestures for OS X Leopard. Well it seems Apple has even more four finger gestures planned, which may coincide with Snow Leopard's release this summer. While trying to hack my system files to reverse the two gestures currently available, I ran into this unused .nib file.
This may hint at a new four finger gesture tab under the trackpad settings that would allow you to customize the action effected. This is similar to the current Exposé and Spaces Preference tab that allows you to use hot corners to call different commands. The file can be found at: