This is already public knowledge: the code name for Fedora 12 is going to be Constantine. If you voted for it thinking about the Keanu's movie, I have some bad news for you: the F12 theme will not be based on that, it will not gonna happen.
My first reaction is to go straight to the source: Constantine the Great, the famous Roman emperor, which was "first" for some things, had some "features" and also provided some "freedom". And for me that Constantine equals Byzantine culture, best represented by Byzantine mosaics, something like:
see more; photos by Gauis Caecilius
published under a CC-BY-ND license
The real trick is to take out the religious implications (which are bad) and leave in the cultural references (which are good). And I think there is potential in a visual conflict in a contrast of old mosaic style and modern imagery (4 F's?), everything with a shade of blue.