I tend to agree with Don’s original point in his Pragmatics post. REST vs. SOAP is mainly about reach of services and not much else. If you know the target platform of the consumers of your service is going to be .NET or some other platform with rich WS-* support then you should use SOAP/WSDL/WS-*. On the other hand, if you can’t guarantee the target platform of your customers then you should build a Plain Old XML over HTTP (POX/HTTP) or REST web service.
Which begs the question: if you knew the target platform of your customers, why would you bother with this whole interop thing in the first place?