Mark did an interesting experiment with a WSDL for a GET-based web service, reprising a similar thing Paul did last year for the Google Web APIs.
Unfortunately, GET-based WSDL doesn't seem to work well. I can't make Mark's WSDL work with either Java's Apache Axis 1.1 or Perl's SOAP::Lite 0.55. Neither seem to find any methods to invoke. There's also an issue of getting .NET to do authentication; that may be solvable.
I'm seeing the same problem with Paul's Google wrapper. WSDL is one of those squishy specs where stuff may be 'correct' but it doesn't work with any of the tools. I suspect the issue here is since no one is using the GET binding, it just doesn't work in many places. Frustrating situation.