The rich and robust set of server management capabilities in Windows Server AppFabric apply only to Windows Communication Foundation (WCF) or Windows Workflow Foundation (WF) services built using .NET Framework 4. If you have access to the source files for the existing .NET 3.X WCF or WF service assembly, to leverage the AppFabric capabilities the recommended option is to rebuild the assembly using the .NET Framework 4 libraries. During this process you also may be able to use some of the new features of the .NET Framework 4.

In the case where you only have a legacy .NET 3.x binary assembly containing a WCF service you can move it to CLR 4 application pool and leverage the compatibility libraries for the .NET 3.x applications included in the .NET Framework 4.  To do that you can open the website or project in VS2010 which will automatically kickoff migration and convert the .NET 2.0/3.0 specific configuration to .NET 4 schema. Once that is completed you should rebuild it to make sure it compiles correctly and then deploy. Note.NET 4 no longer supports <System.ServiceModel> <ServiceHostingEnvironment> </System.ServiceModel> section inside a virtual directory or folder. It is required to be under the virtual application.

In the case of a WF service you have two options. One is to keep the service intact but migrate it to the CLR4 application pool by repeating  the steps described above for the .NET 3.x WCF service. The second option is to migrate WF3 (System.Workflow) artifacts to WF4 (System.Activities). For more information on how to do that, refer to WF Migration Guidance:
WF Migration Kit:   
WF Migration Docs:
For more information on improvements to the .NET Framework 4 Framework libraries for WCF and WF, refer to Upcoming Changes to .NET Framework 4: Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF).