Servicepack 1 for the .NET Framework 3.5 is coming out so there are many new features and improvements… like this list of WCF Improvements:
- New Hosting Wizard for WCF Service projects.
- Enhancements in Test Client such as support for RM Sessions, Message Contract and Nullable types enables testing of broader set of WCF-based services.
- Expanding reach of DataContract Serializer by relaxing the need of having [DataContract]/ [DataMember] on types and by supporting an interoperable mechanism for dealing with object references.
- Improved Partial Trust Debugging Experience with support for Event Log.
- Support for ADO.NET Entity Framework entities in WCF contracts.
- Improvements in writing REST based services ranging from easily supporting ServiceDocuments publication and consumption to providing greater control and usability of UriTemplate.
- Significant performance improvements on large workflow-based projects in Visual Studio.
- Considerable scalability increases for hosted WCF services in IIS7-integrated mode.
Source: http://hyperthink.net/blog/we-are-pleased-to-bring-you-new-features-in-net-3-5-sp1/