Last year's 13-inch MacBook Air was an already-stellar battery performer, but the 2011 version takes another leap forward. In our video-playback battery drain test, the actual 13-inch Air ran for 7 hours and 27 minutes, that's 41 minutes longer versus 2011 13-inch Air. Employing best battery life we've seen from any current MacBook, and leaves most Windows ultrabooks all of the dust -- the Sony...