I just uploaded [[Image:X client server example.png]]. That's a little network diagram done in Inkscape. So the native form is SVG, which is highly editable and thus makes some sense as a work to distribute under the GFDL - the SVG is the source code, the PNG is just a rendering.
But I can't upload SVG. Is there a good reason for this, or is it just that no-one thought of it?
(SVG is just XML text - I don't know of a way to include malware.)
This goes for other image formats - GIMP, Illustrator, etc. For resources under a license that allows editing, it would make sense to allow upload of the source version.
- d.