Last Saturday Apple released a number of EFI firmware updates for various Mac models, which addressed problems with NetBoot features, the use of HD displays for protected HD content, and boot drive selection when external drives are plugged into the systems. The updates were for Mac Mini, MacBook Air, iMac, and MacBook Pro systems.
After releasing these updates, Apple has issued another update for the MacBook Pro (version 2.7 was released on Saturday; this is version 2.8), which addresses a problem in which 15-inch models from late 2008 developed flickering displays. This fix is only applicable to the 2008 model.
To install this update, you can download the updater through Software Update in the Apple menu (the preferred option), or you can download the standalone installer from the MacBook Pro EFI Firmware Update 2.8 Web page.
Once it's downloaded, run the installer and follow the onscreen instructions to apply it. Be sure your system is plugged into a reliable power supply (do not rely on its battery, especially during a firmware update in which the power source controls might be altered), and then wait for the update to finish completely. During the installation process your system should reboot at least once, but might reboot multiple times if needed, so let it run its course and do not stop it by pressing and holding the power button.
As always, be sure to fully back up your system before applying this or any other update.