Not sure if there are references to this but I've looked. All of my previous laptops before the battery was depleted you'd get a warning message, then the computer would go into sleep mode. The sleep led would still do its glowy thing for quite a bit - like hours, then it would go dim. Typically that's when I'd put it on a power supply to calibrate the battery. The contents would be saved to RAM and you'd have to push the power button and get the "ghost screen" with progress bar and desktop as left before shutdown. If you didn't let it go all the way to deep sleep - say you charged it before the sleep led went out, you could put it on a charger and press the space bar and everything would pop up pronto. No ghost screen. No reboot, just like opening the lid or waking it up after the display went to sleep while open. Now the new MB, MBP & MBA the same thing happens with the exception that the glowy sleep light led goes out almost immediately after shutdown. If I let it sit for 2 minutes or 4 hours, I still have to hit the power button and get the ghost image w. startup bar. Apple hasn't changed their calibration instructions with new computers from old ones. Hitting the space bar after plugging in charger even if one minute after battery dies has no affect, still have to hit power button. Do you really have to let it sit 5 hours or so like I've been used to w. previous notebooks for battery calibration on the new models? I always used the sleep led as a guide as to when to plug it in since when it went out, you knew it was in deep sleep mode. Anyone w. old and new models notice this (or am I being stupid again)?