Forgive a bit of self-advertising, but I also thought some of you genuinely might be interested in this.
My company, ngmoco/DeNA, made a framework that allows you to write code in Javascript and then run it on iPhone, Android, and Flash.
It also (perhaps more importantly) has its own social network (it's the child of the Plus network in the US and the mobage network in Japan) with already has millions of users. Included with that are many Steam-like features, like achievements, buddy lists, etc. It also has a virtual store, so all monetary stuff is taken care of for you, similar to in-app purchases on iTunes (on iOS it does go through the iTunes store).
It's also free to use. I ported most of my game Sinuosity to it as a test in about 1 week, so it's pretty easy to use.
https://developer.mobage.com/How it works
ngCore provides a unified JavaScript SDK backed by ngmoco's ngCore code libraries. This allows for easy, rapid application authoring while still maintaining native performance.
Using ngCore, it is possible to load and run games on demand - once loaded, games are cached locally until discarded or updated. In ngCore all game logic is authored in JavaScript. A complete JS-built game could be bundled with data and loaded remotely within the game service app, much like a downloaded level in a traditional mobile game.
On the Android platform ngCore JavaScript executes using Google's V8 interpreter and attaches to native APIs. On iOS JavaScript executes using the interpreter provided by UIWebView. The performance of the downloaded gamelet is indistinguishable from a native App as it binds to the native APIs, which are part of the master App.
