Users of Canon's camcorders have asked for tools like chdk. There is some work happening on various models.
“Canon has released an update to version 18.104.22.168. Where and how to get the firmware and a serial...HV30 Firmware Analysis
“This HDV camcorder was released in January 2007, and has become a very popular tool for indie...HV20
“The HF10/HF100 is an AVCHD camcorder (saves footage to a SD card in AVCHD format, compared to...HF10/HF100
“Is there yet or going to be a version of CHDK for the Canon FS100? It would make my day if there...CHDK for Canon FS100
“There's an official firmware update available which updates version 22.214.171.124 to 126.96.36.199, and you...HF10/100 Firmware Analysis