This firmware update addresses an issue where trackpad clicks may not be recognized on MacBook (Late 2008) and MacBook Pro (Late 2008) systems.
Apple notes that because this is a firmware update, you will need to follow the on-screen instructions after the download is completed through Software Update (Apple menu > Software Update). If you wish to download the installer file directly, you can do so by going to Apple's update download website. After you install the update, come back here and take part in our poll -- we would like to know if this took care of your Trackpad woes.
Thanks to everyone who sent in this tip!
Apple MacBook Pro 13-inch (early 2015)