I calibrated my battery last night, left it on overnight whilst I went to sleep. When I woke up the first thing I did was plug the magsafe back in. Left it for a few minutes to get the battery a bit charged then pressed F2 to un-dim the display and then wiggled the mousepad. Everything came us as normal (as it always does). However, since it was pretty dark in my room I noticed that a little green light under the Macbook going on and off. I have never seen this before, but when I turned the room light on you can't see it. So I turned the Macbook over and it is one of the lights on the battery - there are about 6 little lights and only the bottom one is flashing. The light only flashes when the magsafe is plugged in, which would leave me to believe that it just means the battery is charging. Just to be on the safe side (with all these batteries blowing up all over the place) I switched it off before going to work, so I don't know yet if when it becomes fully charged the flashing will go away - the battery charged percentage was I think around 30 when I left. The Macbook is in perfect working condition though, I still had all my windows open which it came back from sleep, was connected to the Internet, a restart worked fine. Is this normal? I have never noticed it before but I could be wrong. Oh, and I haven't installed the battery update, I was actually going to do that this morning, which is pretty ironic.