Power Nap – keeps your Mac up to date while it sleeps

Apple has created a new feature for its latest OS X Mountain Lion operating system that promises not only to get your email while your computer is closed and dormant, but also back up your Time Capsule and download new system updates.

The new feature will work silently and without your knowing, says Apple. It'll be compatible with the second-generation MacBook Air and MacBook Pro Retina display models.

Judging by the app icons Apple demoed on the screen during its WWDC event in San Francisco, the new feature will work with Notes, iPhone, Reminders, Calendar, Find my MacBook and Mail. It'll even happily sync with your Photo Stream.

Apple's OS X Mountain Lion will be available in July, but it will be a free upgrade for the new MacBook Air and Pro notebooks also revealed at WWDC if they are bought from today.