I recently began a project in which I wanted to consume and use the REST data services offered by SharePoint 2010 only to find a wonderful error waiting for me to be discovered. Browsing to the service (http://<server>/_vti_bin/listdata.svc) in a web browser provided this response:
After some fairly quick Google searches, I discovered there is a service pack release that must be installed to enable this service. The name of the service pack release is ADO.NET Data Services Update for .NET Framework 3.5 SP1 for Windows 7 and Windows Server 2008 R2 and can be found at the following URL.
Installing this update will require a reboot of the server. Once the service pack has been installed and the server rebooted, I received a much different response:
This means the service is now setup and running correctly. You should be able to point any VS studio project to it and retrieve the list of results.