Apple has a firmware update for the trackpads of the new portables.
This firmware update addresses an issue where trackpad clicks may not be recognized on MacBook (13-inch, Aluminum, Late 2008) and MacBook Pro (15-inch, Late 2008) computers.
The update program starts automatically once the installation has finished. Follow the instructions to finish the procedure for this update. (If the update asks to restart the system, the update program will restart after you have reopened your session)
Further info can be found at: http://support.apple.com/kb/HT3288
[translation by crispin]