If you are regular follower of MS ASP.Net events and news, this could be older news for you. J
Yes! MS has announced that they have released another set of MVC 4, ASP.Net Web API, and Web Pages with Razor Syntax under open source umbrella (Apache 2.0) and developers can now contribute to this community.
Source code http://aspnetwebstack.codeplex.com – Live RC
Browse the source code here – http://aspnetwebstack.codeplex.com/SourceControl/BrowseLatest
We can now dig further inside the code and contribute to this community.