SecurityNegotiationException in WCF Services

Many people including myself are running into this problem while sharing and running WCF samples using the .NET Framwork 3.0 RC1.  If you receive the following...

Exception
[System.ServiceModel.Security.SecurityNegotiationException] {"SOAP security negotiation with 'https://localhost/OrderService/OrderService.svc' for target 'https://localhost/OrderService/OrderService.svc' failed. See inner exception for more details."}

Inner Exception
[System.ComponentModel.Win32Exception] {"The Security Support Provider Interface (SSPI) negotiation failed."}

Try changing <userPrincipalName value="MACHINENAME\ASPNET" /> to <servicePrincipalName value="host/localhost" /> in the client config file.