From Jason Snell's (MacWorld) review: ``Apple is making a big deal about saying that these new MacBook Airs have “instant on” technology. I haven’t had a chance to do a lot of testing, but it seems that what the company is talking about is a new power-saving mode. After it’s asleep for a while, the laptop switches into a super power-saving standby mode that lets the battery survive for up to 30 days. But when you open the laptop back up, it doesn’t show you a progress bar while it loads stuff—it just snaps back to life. Or so they say. I’ve been too busy actually using it to figure out all these permutations. Stay tuned.'' The bolded part says that the MacBook Air essentially goes into deep sleep (or hibernate mode) after it's been light-sleeping for a while, so there's not really a need to indicate that it's sleeping. Unlike other Mac notebooks, which need a power button press to awaken from deep sleep (as a result of running very low on battery charge), the MacBook Air will automatically arise from deep sleep after the screen has been opened (detection done by hinge movement). Hopefully this explanation helps, and if not, criticize away!