I happen to be browsing some other game dev news last night and I came across this article from Facepunch Studios, the guys behind Garry's Mod and Rust.
They are rewriting Rust and using HTML 5 for the UI.

http://www.pcgamesn.com/rust/rust-rebooting-heres-why

It seems as though they are embedding the chromium web browser into the engine:

Garry Newman is using Coherent UI in Rust, which is HTML5-based multi-platform user interface engine for games. There are already hundreds of projects using Coherent UI which proves the stability of HTML5-based plugin in game UI. You can check Planetary Annihilation by Uber Entertainment, which UI is 100% powered by Coherent.

What I did today, that may be of some interest for anybody else attempting this:
Investigated the Chromium Embedded Framework, a simple way to integrate Chromium in to any application.
CEF3 is provided as prebuilt binaries, but unfortunately not for VS2012. So I had to build my own.

Integrating CEF is a good alternative, especially for small projects. We've investigated it in a details and wrote an analysis on What should developers consider when using Chromium Embedded Framework (CEF) in their games? I would love to hear your feedback on it. Please find it here

Integrating CEF is a good alternative, especially for small projects. We've investigated it in a details and wrote an analysis on What should developers consider when using Chromium Embedded Framework (CEF) in their games? I would love to hear your feedback on it. Please find it here

Yeah I came to the same conclusions as you after looking into CEF for a few days. The lag, and the cost of pixel transfer make it fairly limited for all but the simplest UI. The system you have is exactly what I would like, but unfortunately way out of my price range for a hobby project. I also looked briefly at Awesomium, including downloading and running their demos, and they barely offer anything beyond what CEF offers as far as I can tell. They still use multiple processes, and can't handle rendering more than one fullscreen target at a time.

My solution is probably going to be rolling my own layout and rendering system, with Javascript V8 integrated. Start with something simple and then developing it in parallel with the rest of my project. Obviously it won't cover all HTML5 and CSS3 features, but then they aren't all required for a game UI. I do think that Adobe have it right with Flash and Edge Animate, with respect to their "everything is animatable, and all actions are animations" approach. Once I started thinking of UI as a state graph with animations along the edges it starts to seem like a very powerful and coherent approach (although maybe it is an oversimplification for some scenarios).