I did a quick search about this and didn't find anything, so I'm posting here to see if anyone else had this happen. I updated to Mountain Lion yesterday with the rest of the world (I love it!), and after waking my 2011 27" iMac from sleep this morning, 2 finger swipe for Notification Center, 3 finger swipe for Mission Control, and 4 finger pinching in and out for Launch Pad, etc wouldn't work. Swiping within Safari still worked (2 fingers to go back, pinch to zoom, etc), but nothing outside Safari would. Has anyone else experienced this with Mountain Lion yet? Any ideas on how I could fix this, or is this just a bug that Apple needs to address? Thanks!