In addition to my SD700IS, I also have the HG10 camcorder. This camcorder does HD, has a hard disk as well as a Mini-SD slot, and uses the DIGIC III chip. It's "still photo" capability is quite similar to regular Canon compact cameras so it may be that the porting might be doable.
I'm a programmer but haven't done anything like this in decades. Hopefully this process might be easy...I'll look thru the forum postings to see what I can find. Any advice would be appreciated...