Via Software Update, Apple yesterday released a slew of firmware updates addressing performance and reliability of all Core 2 Duo and Xeon Macs and fixing issues with Boot Camp. There’s very little information available at this time definitively showing what exactly these updates do. My guess is that they will disable any Boot Camp beta installations on Leopard’s release date (per the End User License Agreement, or EULA), fix some of the few remaining issues with Boot Camp, and make last-minute adjustments for Leopard.
Whenever firmware updates are released, Jon and I take heaps of tech support calls from customers who need help applying the updates, or resuscitating their computers after a firmware update fails.
Clear, step-by-step instructions for installation will be presented on-screen once the update is ready for installation. I recommend that you print these instructions before proceeding with the update. Additionally, you should burn yourself a copy of the latest Firmware Restoration CD, available here: http://www.apple.com/support/downloads/firmwarerestorationcd14.html
If, for whatever reason, the firmware installation fails, you may use the Firmware Restoration CD to bring yourself back to where you were, and try again to apply the update. Almost 100% of the time, firmware updates are installed quickly and without issues. In a tiny fraction of cases, the firmware installation will fail, and the firmware restoration will fail. If that’s the case, don’t bother waiting on hold with Apple—give us a ring, or just bring your computer to one of our stores—and we will replace your logic board post haste.
If you’re not close to us, you can find authorized service providers near your home here: http://www.apple.com/buy/locator/service/