FireGesture disabled for me as incompatible :'(
Their an easy fix to allow the down grade extension to work on FF5 while you wait for the new to come out.
1. Click onto tools and then click onto Adds-on.
2. At the top middle screen where you see the word about:addons, type in
about:config click on the tab button.
3. Right click button on your mouse and select new and than pick boolean, enter the preference name to
extensions.checkCompatibility.5.0 and then pick
false and your done close the adds-on section and FF and run FF again.
4. Go back and check if your old extension set to enable while you wait for the new version become available
5. OR reinstall the old extension.
Enjoy