Comment 29 for bug 487749

You are correct, it's not just the touchpads of the Synaptics brand, which all support multi-finger gestures, that have their drivers in the xserver-xorg-input-synaptics package. Also ALPS touchpad which do not support these gestures have drivers in this package.

Good that you have started to clean up in the bug-tracker, I had since long lost all hope of ever getting an answer to this bug.