WindowsCommunicationFoundation (WCF) was formerly code named Indigo.
See http://msdn.microsoft.com/en-us/library/vstudio/ms735119%28v=vs.90%29.aspx for its documentation.
MicrosoftWay - EnterpriseServiceBus (ESB) alternative
WCF together with BizTalk is a "superset" of ESB, according to Microsoft.
ZapThink? wrote in 2005 that WCF "is essentially a framework for building a whole range of different tools, including ESBs." (http://www.zapthink.com/2005/08/31/microsoft-pitches-esb-alternative/)
See MicrosoftIndigo for names of key subcomponents.
See also MessageOrientedMiddleware