Hooray!
The Canon A720is has been ported to the current Allbest version of CHDK and it seems functional in my camera (I am not an expert)...
You can
read about it in this thread... Post 145 (on page 10) points to the camera file and a small windows program to make the SD Card bootable.
One warning, if you have SD cards larger than 2GByte in size, you will need to format them as FAT 16 (which normally supports a maximum of 2GB cards) for the CHDK program to be booted in the camera.
Since the A720is uses a new OS (Canon's "DryOS") that has been successfully ported--hopefully that means some of Canon's other new cameras will be ported soon (within weeks or a couple of months).
Now to read about how to use the details of CHDK.
-Bill