I think an official .exe wrapper using Awesomium would be moderately easy. Combined with something like UPX you could support a single exe binary for Linux, Windows, and Mac exports right off the bat.. Plus it is based on Chrome so would have good performance, sound compatibility, etc.
I've been wanted to make a wrapper generator which takes a C2 folder and generates a .exe but just too busy!! :-(
This has been on my mind constantly for the last few days.
I've been thinking about what is really important when it comes to the delivery method of the game. And, in the end Ashley's assurance that all the current annoyances and limitations of browsers would eventually be fixed just didn't reassure me. I think maybe the thing that really bothers me is that browsers do other things... many things at once - and almost all of these things conflict with the purpose of playing the game.
It's like the difference between watching a movie on TV, and watching it in the cinema. Control over the environment is an important part of the presentation of any media, and when movies are sliced up by advertising and cropped to fit a small screen... you're essentially fighting for the attention of the viewer, and often losing.
While all of the annoyances that I previously mentioned are part of this, the biggest is essentially that a browser is the TV, an EXE is the cinema, and an HTML5 EXE wrapper is a DVD/BluRay... so to speak.
They can all present the media to the viewer, and they all have different advantages/disadvantages... it would be a sad day if the film industry were to decide, since the future is in digital media, to stop screening films in cinemas.
I would build an Awesomium wrapper myself if I wasn't such a dunce when it comes to setting up Visual Studio (it's almost like they designed it to be a pain in the arse) and had more spare time to learn the basics. Surely, building an application that does nothing but load a single web page (ie, your index.html) would be fairly easy (any takers?).
It would be a start, at least until an official exporter is (or isn't) added.