I had the good fortune to attend the PDC pre-conference and was able to attend a day-long WCF session with Juval Lowy and Ron Jacobs. Juval went first and spoke for most of the day. Juval has been working closely with Microsoft for quite some time, and his COM(+) roots were showing big time. Essentially, Juval is of the opinion that WCF is a .NET killer and should be the way ALL applications are written from here on it. As Juval has extensive expertise with COM, I think he tends to see everything in terms of that model, and he may have a point. As a result, he made the bold statement in the pre-conf session of referring to WCF as a .NET killer. While I'm not prepared to follow Juval in claiming .NET dead at the hands of WCF, he makes some good points. If you think of the communication between objects in a system analogous to the communication of services in an architecture, WCF provides some cool abilities that the traditional model in .NET does not.