Mountain Lion offers a new feature called Power Nap, but since it’s limited to only a few recent laptop Mac models, most people probably haven’t seen it. In short, Power Nap enables supported Macs to wake up briefly to back up via Time Machine, check for email via Mail, receive new messages in Messages, and update iCloud-related data, including calendar events, contacts, reminders, notes, iCloud documents, and photos in Photo Stream. Over at Macworld, our friend Dan Frakes explains just what Power Nap can do, how you use it, why it works on so few models, and more.