I suspect this problem has surfaced in the last three years because I never used to have this problem when I first got my camera. I've tried everything suggested here and nothing works on either my macbook or my wives.
However, I seem to have found a solution - finally.
Boot up in windows, copy compact flash to usb stick. Not very ideal, but it's less infuriating than having constant ejection whilst trying to import to iphoto. My wives macbook has xp on it installed via bootcamp, and the compact flash reader doesn't eject on whilst on that os. That does suggest to my limited knowledge it's an operating system issue.