A recent discovery in OS X Leopard’s system files sheds some light on Apple’s intentions on letting users customize their own four-finger swipe gestures. While their has been talks on software updates allowing users of older machines to get enabled gestures, customizing your own has never before been an option.
MyAppleGuide originally found the file (though we first saw it over at MacRumors), which we opened up in Interface Builder to snap the screenshot below.

While none of these new features have been discovered in developer builds of Apple’s upcoming Snow Leopard operating system, readers have previously discovered that Snow Leopard may be bringing four-finger gestures to older Macbooks through software updates. The notion that Snow Leopard might ship with the ability to customize your own gestures is not far fetched.
To find the file navigate as shown: /System/Library/PreferencePanes/Trackpad.prefPane/Contents/Resources/English.lproj/FourFingerSwipeGesture.nib