I tried connecting a Powershot G2 camera to my new 15" Powerbook and iPhoto wouldn't recognize the camera. I have no problem downloading pictures off it with Windows.
Well, it doesn't seem to be iPhoto because the PowerShot G2 appears on this webpage. Make sure you have the camera on and then plug the camera into you PowerBook. Also, go to the Image Capture application in your Applications Folder. In Image Capture preferences - (Image Capture Menu -> Preferences) make sure that the choice to open iPhoto is selected under the Camera tab. If none of that works, you'll have to get more specific in what's happening.
Ok, I've figured out something. If I'm configured to a standard or admin account, there's no problem. I've I'm configured to a managed account it doesn't work.