See the Sticky: http://photography-on-the.net/forum/showthread.php?t=50967
Man! I thought this camera (1DMKII) turned on fast before! As soon as you hit the switch this baby is ready to go NOW! It's immediate. Very impressive. And they've improved AI Servo tracking too!! That's a bonus for us sports shooters for sure, and the tracking was awesome before! I have to go shoot some winter motocross now or something.
Way to go Canon!!!