So I've only had my e-p1 for about a week. The first time I heard the IS turn on I was left wondering "what is that horrible grinding noise?" It mainly confused me because I didn't hear it all the time. After some searching, I believe I read that IS does not turn on if the shutter speed is above 2 seconds. (and it seems audibly true on my e-p1). After some playing around... I'm under the impression that there's a minimum shutter speed at which the IS also doesn't turn on - but I'm not quite sure what it is... does anyone know what the shutter speed range for IS to turn on is?