TFS has very nice SDKs for building both .NET & Java applications for it. However, some platforms – particularly some devices don’t support those SDKs. On those platforms, often the easiest way to access a service is with REST or Json. Brian Keller recently blogged about an update to his OData service for Team Foundation Server 2012 that exposes OData end points. He also described a sample Windows Store app built with it.
You can read more about it here: http://blogs.msdn.com/b/briankel/archive/2013/01/07/odata-service-for-team-foundation-server-v2.aspx
In the coming months, we’ll also be hosting this OData endpoint on our Azure infrastructure and exposing your Team Foundation Service projects to you in this way. Of course, since Team Foundation Service projects are private, their OData feeds will be too.