Richard Turner (a Product Manager in Microsoft's Web Services Strategy team), has published the first of a series of papers that provides guidance on how to best use Microsoft Web service and distributed systems technologies in order to build distributed, service-oriented systems using today's platform.
The first paper, “Developing Distributed Services Today”, can be now found on MSDN, at this link, with more on the way very soon.
A very good read and I would highly recommend.
– Paul
[updated link, as the paper has moved]
http://msdn.microsoft.com/webservices/choosing/default.aspx?pull=/library/en-us/dnwebsrv/html/dsgprescriptiveguidance.asp