Microsoft recently released a tool that allows you to expose an OData service for Team Foundation Server 2010. This sample helps developers work with data from Team Foundation Server on multiple types of devices (such as smartphones and tablets) and operating systems.
OData provides a great solution for this goal, since the existing Team Foundation Server 2010 object model only works for applications developed on the Windows platform. The Team Foundation Server 2010 application tier also exposes a number of web services, but these are not supported interfaces and interaction with these web services directly may have unintended side effects. OData, on the other hand, is accessible from any device and application stack which supports HTTP requests. As such, this OData service interacts with the client object model in the SDK (it does not manipulate any web services directly).
To know more, watch a video on how to expose an OData service from TFS 2010