I'm thinking of replacing my 3G iPad 2 with a MacBook Air, but I'd want to have Internet on the go, so I would get the AT&T tethering plan and tether my iPhone 4 to my MacBook Air wirelessly. My experience with Android phones has shown me that tethering kills the battery FAST. But I've never tethered with an iPhone. How bad of a battery drain will tethering be on an iPhone 4? And what are your experiences with tethering? Anything I should be aware of?