Hard coded multitouch desktop gestures for Ubuntu/GNOME. To use it, enable the Dbus/Scale/Rotate plugins in Compiz.

LinuxMultitouch.py

from pymt import *
import sys, dbus, subprocess, os
import time

class Tracer(MTWidget):
    SWIPE_X_THRESHOLD = 220 
    SWIPE_Y_THRESHOLD = 100
    LEFT_SWIPE, RIGHT_SWIPE = range(2)

    block = False

    def dbus_message(self, plugin, action):
        try:
            rootwin = subprocess.Popen(['xwininfo', '-root'],
                                       stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()[0]
        except OSError:
            raise SystemExit('Error: xwininfo not present')

        try:
            rootwin_id = int(rootwin.split()[3], 0)
        except IndexError:
            raise SystemExit('Error: unexpectedly short output from xwininfo')
        except ValueError:
            raise SystemExit('Error: unable to convert "%s" to int', rootwin.split()[3])

        service = interface = 'org.freedesktop.compiz'
        session_bus = dbus.SessionBus()

        args = ['root', rootwin_id]

        proxy = session_bus.get_object(
            service, '/org/freedesktop/compiz/%s/allscreens/%s' %(plugin, action))
        obj = dbus.Interface(proxy, interface)
        obj.activate(*args)
    
    def on_touch_move(self, touch):
        if touch.y < 150:
            return
        if touch.x < 100 or touch.x > 600:
            return
        if self.block:
            return

        if len(getCurrentTouches()) == 3:
            if (touch.y - touch.oypos) < -self.SWIPE_Y_THRESHOLD:
                self.block = True
                self.dbus_message("scale", "initiate_key")
                return
            if (touch.y - touch.oypos) > self.SWIPE_Y_THRESHOLD:
                self.block = True
                self.dbus_message("core", "show_desktop_key")
                return

        if len(getCurrentTouches()) == 2:
            if (touch.x - touch.oxpos) > self.SWIPE_X_THRESHOLD:
                self.block = True
                self.dbus_message("rotate", "rotate_left_key")
                return
            elif (touch.x - touch.oxpos) < -self.SWIPE_X_THRESHOLD:
                self.block = True
                self.dbus_message("rotate", "rotate_right_key")
                return
    def on_touch_up(self, touch):
        self.block = False

runTouchApp(Tracer())