Linux Software for Digital Cameras?

Elbie asks: "I just received a digital camera as a gift, but the only software that comes with it is for these two OSes which look pretty alien to me. How can I get those pictures out of my camera (Canon PowerShot A5) from my Linux box ? Is there any Linux software out there, and if not how to figure out what protocol is used (it uses a standard serial cable to communicate with the PC)"