I don't think you will find many digital or standard cameras that don't have a delay for the auto focus part. Only way I can think it to set the camera on manual focus- and not all digital camera have that capability. I don't know about the Canon S1..maybe someone can help you out on that info.
You can always prefocus the camera and continue to hold the button halfway down...until whatever you want to take a photo of gets moving or whatever. That is what I have to do to catch my kids in a photo when they are smiling or whatever. Otherwise, I get frustrated like you and end up cussing the camera because my pic was actually taken 1 second AFTER they stopped smiling,etc.
