See the article at http://www.xml.com/pub/a/2002/02/06/rest.html by PaulPrescod for an eloquent argument on why SOAP RPC violates the RestArchitecturalStyle.  A quote from the article says: "''SOAP RPC is DCOM for the Internet.''".  

There's lots of discussion on the W3C TAG mailing list about it.  See for example http://lists.w3.org/Archives/Public/www-tag/2002Mar/thread.html
-- AndrewJoyner
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CategoryCommunicationProtocol