I'm pretty sure that all edits that you do in iPhoto are on a processed copy of the original (which is why the iPhoto library can grow so fast). You should notice folders of originals and then also another folder with the edited versions. This lets you revert your edited photo to the original at any point (as long as you haven't deleted the original).
wulf, what benefits does it have running the virtual Linux box and using the Gimp compared to using the OS X version which uses X11? Is it just so that you can use ufraw? Just curious
