On the subject of turning the camera on, my 400D's battery lasts so long* I never bother to turn it off because I'll be sure to charge it before an event anyway. In fact it's really annoying when someone tries my camera or looks at pictures on it and turns it off before handing it back to me. The only problem with this is that is doesn't regularly do the sensor shake thing.
* If I'm away from electricity it will even last almost a week with moderate usage.