Fix for Canon Camera Window and OSX 10.4.7
It seems that the recent update to OSX (10.4.7) broke Canon's Camera Window software. While there doesn't seem to be an official fix for this at the moment I've found a work around which is almost as good. Plug the CF card into a normal USB card reader, the Camera Window software seems to recognise it as if you had plugged in your camera. After all the camera is probably only acting as a USB storage device anyway.
Hopefully Canon will fix this soon, I don't think it's a problem with OSX as such.