If you have a Mountain Lion machine eligible for Power Nap, one of OS X's new marquee features, you should check Software Update (via the Mac App Store) to make sure you've got the latest firmware.
The enablers for the 2011 MacBook Air machines and the 2012 models were released on July 25, and the SMC update for the Retina MacBook Pro arrived on Friday. Apple has posted all three enablers on a single page.
