There may be some hope for older Canon camera support, like the G1. I have a G2, which is also not supported. But the G3 is a supported camera.
Well, it turns out there is a system file that you can edit to "add support". It's described here :
http://discussions.apple.com/thread.jspa?threadID=262930
I tried this for the G2, and sure enough, it worked. I do not know how significantly different the RAW file format between the G1 and G2 is, but if they are not too different, you may find that changing the G2 to a G1 in this file may work for you.
Note that while this 'hack' seems to work, I'm not convinced that it is the optimal RAW converter for the G2 (or G1). I find the conversions a bit on the dark side, but these can be compensated for through later adjustements (albeit while adding some more noise in the shadows).
Until Apple adds more formal support for these older cameras, you may want to give this a try yourself for the G1.
Sure wish someone knew what all the numbers meant in these files so we could tweak the parameters and improve the Raw conversions. But, they are not too bad for my G2.
Hope thi helps!