SLOphoto1: The Manual setting does NOT "offer[s] the complete flexibility of full manual control" for the SX40. There is now a governor on it. Try to set the ISO at 400 for a night shot, and then spin the dial towards a 15 second shutter speed. It stops it at 1 second and drops the ISO to 100. Then a message appears on the LCD which says, "ISO speed is limited due to slow shutter speed." I verified it with Canon today. Canon also verified that all previous Canon cameras DID allow full Manual control in setting both the ISO and shutter speed, but no more. This has halted a large portion of the sunset and night photography I have been doing of the Monterey Bay Harbor for the past 2 years. It is condescending and insulting to long-term Canon users to presume to say to us, "We think you don't know what you are doing, and we are no longer going to let you use those traditional manual settings anymore." Obviously if we use a Manual setting it is precisely because we DO KNOW what we are doing!
Were you ever able to try your Milky Way shot using the CHDK? If so, were you successful? Please give some details on your settings.