Mid-2011 iMac graphic firmware update 2.0 fixes startup issue

Apple just posted a firmware update for mid-2011 iMacs, which you can find in Software Update or here. There's a knowledgebase article about the issue here, but basically, if you've had symptoms of your mid-2011 iMac showing a white or gray screen and being unresponsive on startup, this update is supposed to fix the problem.