There are a number of posts similar to this. I recently experience my Magic Mouse losing its right-click function. I thought it was something wrong with the mouse itself. Coincidentally, I also recently got a trackpad for the iMac and the right click feature there wasn't working either, so I presumed it must be the iMac itself of the system software. I was already running Mountain Lion 10.8.3, but on a whim I donwloaded the 10.8.3 Combo Update from Apple and installed that over my existing installation.
Presto ! The mouse and the trackpad are now working. So happy.
Haven't really used a trackpad much with the iMac, and I do not have a laptop. I am actually starting to like it better than the mouse.
Liking the iPad Mini also. I works pretty well as a laptop when I am travelling, and if I carry the wireless keyboard and the trackpad with me with the iPad Mini is works pretty well as a little laptop. With all of the apps out there there is a plethora of gadgets, in some respects better than those available for the Mac itself.
I installed a little VPN thingy to give me access to my iMac at home, which is virtually always running, in case I need something remotely.
Parenthetically, I got onto all this because I had to bring the 27" iMac, only 1 year old, in for repairs, overheating with the fans running wildly. I kind of suspected that it was the CPU fan the SMC Fan Control thing indicated that my CPU fan speed was 0. That is what the tech said. Have to wait for the part to arrive yet though. Thank got for the mini. I miss my iMac.