When upgrading a F-12 system to F-13, if you have a transparent background in your gnome-terminal, the amount of shading gets reversed. (Also, both ends of the shading scale result in completely unshaded) This looks like: https://bugzilla.gnome.org/show_bug.cgi?id=615417 We should make sure we have this fix.
The fix is included in vte-0.24.1, which is in updates-testing. You should give it karma to get it in.
vte-0.24.1-1.fc13 has been submitted as an update for Fedora 13. http://admin.fedoraproject.org/updates/vte-0.24.1-1.fc13
vte-0.24.1-1.fc13 has been pushed to the Fedora 13 stable repository. If problems still persist, please make note of it in this bug report.