Apple has released Hard Drive Update 1.0 which includes bug fixes and important updates for the following systems:

•iMac Core 2 Duo (Mac OS X 10.4.7 or later)

• Mac Pro (Mac OS X 10.4.7 or later)

To complete the firmware update process, follow the instructions in the updater application (/Applications/Utilities/Hard Drive Update 1.0.app). The updater will launch automatically when the Installer closes.

Hard Drive Update 1.0 is available via Software Update and also as a standalone installer.

More info and download link (1.4MB) here.