Apple released Xserve EFI Firmware Update 1.1 on Monday evening. The firmware update requires Mac OS X 10.5.2 or later, and Appleis ever-insightful release notes only state that it "fixes several issues to improve the stability of Xserve computers."
The installer places an application called Xserve EFI Firmware Update.app in /Applications/Utilities. Running the application installs the new firmware on your Xserve.
Xserve EFI Firmware Update 1.1 is available for download at the Apple Support Web site.