Apple has released new firmware updates for a number of its early- and mid-2011 Mac systems. The updates, which require OS X 10.7.3 or later to install, address problems with NetBoot features, and fix problems with HDCP authentication after rebooting (which may prevent HD content from being displayed on certain monitors). The updates also fix a problem with the selection of the boot drive when a USB drive is plugged into the system.
The updates should be available via Software Update for iMac, Mac Mini, MacBook Pro, and MacBook Air systems released in early to mid-2011, but you can also download them from the following locations on the Apple Support Web site:
Mac Mini EFI Firmware Update 1.6 (4.08MB)
MacBook Air EFI Firmware Update 2.4 (4.06MB)
iMac EFI Firmware Update 1.9 (3.77MB)
MacBook Pro EFI Firmware Update 2.7 (4.24MB)
The boot ROM or SMC versions of systems after the update is applied will be MBP81.0047.27 for the MacBook Pro, IM121.0047.1F for the iMac, MBA41.0077.0F for the MacBook Air, and MM51.0077.10 for the Mac Mini. These versions can be found in the System Information utility in OS X Lion.
As always, be sure to fully back up your system before applying an update, and be sure to follow the installer's onscreen instructions to ensure that the update gets installed properly.