ADO.NET Data Services is essentially a collection of patterns and libraries designed to simplify the creation and consumption of web-based data services. The framework was set up from the get go to enhance the .NET Framework. During the development process Microsoft choose to react to feedback from early adopters indicating that the company needed to limit the number of Data Service releases. “To address this need we’ve decided to change ship vehicle for release to be an in-place update of data services binaries that shipped with .NET Framework 3.5 SP1 (instead of a SxS release as was case for v1.5 CTP1 release). The release’ll ship as a redistributable update to .NET Framework 3.5 SP1, which’ll include enhanced data services runtime assemblies and an updated datasvcutil.exe command line tool”.
More info: ADO.NET Data Services