I bought an oldish MacBook 13" Unibody (late 2008) and when I got it one of the first things I did was to install Mac OS X Lion.
Everything was working fine, until I applied an update that made the trackpad stop working (it only accepts clicks, no touch is recognized).
This is the "Trackpad Firmware Update" from the automatic updates (link below).
When starting this firmware update a window appears with a status message, Cancel and Update buttons. After clicking the Update button, it starts installing, appears to complete, status changes to Finishing..., and Update button comes back active at some point.
After that I have tried (unsuccessfully):
same thing, but using the 'root' account
leaving the computer on overnight to see if actually "finished" the process
Hand palm pressing over 30 seconds on the trackpad (read this on another thread...?)
Reinstalling Mac OS X Lion using a DVD
Indifferent to USB devices being connected or not
I've also tried most (or all) of this after reverting to Snow Leopard.
I'd be thankful for any ideas to try out.