Users of Canon's camcorders have asked for tools like chdk. There is some work happening on various models.
“There's an official firmware update available which updates version 220.127.116.11 to 18.104.22.168, and you...HF10/100 Firmware Analysis
“This HDV camcorder was released in January 2007, and has become a very popular tool for indie...HV20
“HD camcorder based on the HV20, the HV30 offers some physical body improvements as well as a new...HV30
“The HF10/HF100 is an AVCHD camcorder (saves footage to a SD card in AVCHD format, compared to...HF10/HF100
“Canon has released an update to version 22.214.171.124. Where and how to get the firmware and a serial...HV30 Firmware Analysis