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!"
For $500, the iPhone seems like a better and better deal every second. My N95 cost roughly $750 and has various pros and cons versus the iPhone, and if I didn't need to have a phone that can travel with me I'd totally buy one just for the fun of it. Too bad revision b is releasing in Q4, with various speed and internet connectivity improvements. Perhaps I'll buy one then and at least enjoy it in the States!