I attended Frank Mantec's (Google inc.) talk today at XTech 2007 on Google Data API (see: http://2007.xtech.org/public/schedule/detail/33). He had made a very surprising claim:
"SOAP is a dead duck in the www"
And he said it as someone who worked for Microsoft for years and developed from scratched the WSDL. He was saying that interoperability across programming languages that are not from the same vendor (e.g., .NET languages and Java) is close to non existing and that the chances that it will be easy to connect via SOAP across languages and vendors is 0.00something% chance to happen. He said that WSDL was and still is a BIG MISTAKE.
Finally, I don't feel that I'm the only one who was not able to make C, .NET, Java and Perl talk SOAP together without ugly "magic" and some "voodoo"and though that the reason for that was WSDL...
All this happened when questions from the audience came asking how come ATOM and REST approach was used rather than SOAP for the Google Data API.