Wish I had even a dinky Canon to try this on. I've been using an older little Fujitsu for the past few years that has a surprisingly robust feature set for a point and shoot (RAW mode, exposure bracketing, reasonable manual exposure control, etc.) but some of the possibilities with the CHDK are amazing--I'd kill for the range of shutter speed settings alone.
You've probably already been to the CHDK site; if not, they have some pretty decent guides and instrictions: http://chdk.wikia.com/wiki/CHDK
Hackaday, one of my favorite sites in the "Holy shit that's amazing--I suck because I could never do that" category, was where I first saw mention of the firmware, I think. They have a more general overview on the some of the possibilities.
I'd love to hear how it works for you; I've had my eye on some decent midrange Lumix models for a while that strike a balance between my desire for a decent camera to indulge in artsy-fartsy pretensions and a price worthy of my no-doubt incredibly amateurish skill. But if I could get all the fancy bells and whistles off of a $50 craigslist find, that may be better in the end.