This is a question that bothers me a great deal - with all the flourishing of Open Source, are our systems on average getting more Open?
Why not go a step further and ship the camera with a grandma-friendly firmware but host an open source community which provides various Canon-curated firmware versions? What could be done to make Canon's cameras suitable for even more cool hacks? How could this not sell cameras? Those most trusted by non-techies to recommend products surely would hold more favorable opinions of those cameras as a result.
Last time I've heard of it, no DSLRs was supported, only PowerShots. It looks like they managed to get custom firmwares working for the 400D, 550D and the 5D mkII — still all very alpha stage, but that's very good news. :)