iMac Graphic FW Update 2.0
Apple has released the iMac Graphic FW Update 2.0 to fix an issue that could in rare cases cause an iMac to hang during startup or while waking from sleep. The firmware update requires Mac OS X 10.6.7, but Apple doesn’t say which iMac models it applies to. Therefore, the easiest approach is to rely on Software Update to present you with the update. As always with firmware updates, be careful not to interrupt the installation process. (Free, 699 KB)
My iMaci7 27" late 2009 gets a response that my computer does not support this software. Also it does not show up in Software Update searches.