Mac OS X 10.6.7 for iMac (Early 2011) and iMac EFI Update 1.6
On the heels of the recent iMac refresh (see “New iMac Gains Thunderbolt, FaceTime HD, and Quad-Core CPUs,” 3 May 2011), Apple has released a couple of iMac-specific updates that address stability-related issues with several apps and interfaces, with a particular focus on Thunderbolt. Mac OS X 10.6.7 Update 1.0 for iMac (Early 2011) 1.0 introduces fixes that improve the reliability of Back to My Mac, App Store, and FaceTime, and corrects issues in Windows file sharing, graphics and video display, and the new Thunderbolt interface. The latter is also the main target of the iMac EFI Update
1.6, whose release notes mention no changes beyond Thunderbolt. But according to Other World Computing, the update also unlocks the full 6 Gbps SATA 3.0 capabilities of the two internal drive bays, though the optical drive bay remains at 3 Gbps. As always with firmware updates, do not disturb or power down your iMac while installing, since it could leave the Mac in a non-functional state. Both updates can be downloaded and installed via Software Update, or through their individual pages on Apple’s Web site. (Free, 382.56 MB and 6.1 MB respectively)
So does this replace the 10.6.7 update or get applied on top of it? The download page appears to say on top of it. But . . .
I just received my new 21.5" quad i7 iMac and was applying all the updates during setup. The iMac shipped with 10.6.6. A bunch of updates are available in Software Update including 10.6.7. Haven't tried anything from there yet. Instead I downloaded the 10.6.7 combo updater and it says that my system drive doesn't meet the requirements. Could it be the updater doesn't recognize the new iMacs yet?
I'm guessing it's applied on top of 10.6.7, but not having a new iMac, I can't say for sure.
With a new machine, I'd let Software Update do the work rather than rely on the combo updater, since it's unclear where in the timeline it was released.