Indigo or WFC ("Windows Communication Foundation") is a stack of new communication technologies running on the .Net platform on Windows Vista, XP and 2003; actually it’s an unification of MS distributing technologies (Remoting, Web Services, WS* specs, Com+, MSMQ);
interoperability is provided by exchanging soap messages ; these soap messages will be xml encoded if a windows WFC application communicates with a no WFC application (like a java app, or any other platform on any other operating system like unix or mainframes) and binary encoded between 2 WFC applications.
WFC will help moving to a world of SOA (Service Oriented Architecture) applications ;
every WFC service is made of :
1.a .Net class implemented in .Net
2.a host (application domain, like WAS : windows activation Services or IIS)
3.one or more endpoints than allow clients to access the service.
You can test WFC beta 1 on the .Net 2.0 SDK beta 2 (for download: goto http://msdn.microsoft.com/webservices/indigo/default.aspx)