The goal of the demo was to show Emscripten's capabilities. Over the last year it has gotten very usable, and can probably compile most reasonable C/C++ codebases (albeit with some manual intervention in some cases). It is my hope that Emscripten can help against the tendency to write non-web applications, such as native mobile applications (for iOS, Android, etc.) or using plugins on the web (Flash, NaCl, etc.). Simply put, the web is competing with these platforms. Emscripten can make the web a more attractive platform for developers, by letting them use their languages of choice, such as C, C++ or Python (without necessarily compromising on speed: the code generated by Emscripten can be optimized very well, and it is my hope that things like type inference will make it very fast eventually).