I have a very practical issue. I would like to install CHDK on say a Canon G1 X. I could buy the camera and then use different methods to figure the firmware version as mentioned on this web site. My problem is that my cameras firmware version may not have a CHDK that can be downloaded for my camera. Is there any way that I can figure out the camera firmware version before I purchase the camera.
Unfortunately - no. The SDM group (an early CHDK spinn-off project) at one point was trying to track serial numbers of some cameras (the S90 or S95 I think) to determine what serial number ranges corresponded to which firmware versions. I think it fell apart due to the lack of work and/or all the firmware version being ported.
Best you can probably do is try to take a picture on your own SD card and then use ACID to analyze it.