Apple introduced Power Nap, a new feature of OS X during today’s WWDC 2012 keynote. Available on the MacBook Air (2nd gen) and MacBook Air with Retina Display, this feature runs backups and “keeps data up to date” while the computer sleeps. Apple notes that Power Nap is silent and power efficient. This post will be updated as more information becomes available. In the meantime, follow our meta live blog of the event.