Let the hive mind of Engadget get that for you.
"We need a digital camera that can be switched on and fire off that first shot fast. It's not a commonly tracked statistic on any review site, and nobody seems to have this information for every camera. We were hoping other readers could inform us as to what small digital cameras can fire off their first pics in under a second (ideally under half a second). It needs to be small, but mostly, just really quick in operation. Thanks!"
Anybody can make one of these things; just order a first surface mirror (aka one-way mirror or sometimes two-way mirror) and put a black matte and LCD/plasma behind it. Make sure you have enough cooling.