Why not use Javascript/SVG/HTML5 for Linux desktop UI ? It will happen eventually, anyway, Im not the only person saying this.
The browser stack is a better alternative to X-Windows protocol, on balance - you can keep the advantages of client/server separation by using ajax+websockets.
Or go the Node.js route and expose OS parts as Javascript API.
Either way you'll have an environment many more people will enjoy hacking UI on, and therefore better chance of improving Linux desktop.
Although its open source, its still another API that is used nowhere else.. so its expensive for a developer to jump in.