I would say that on the whole SOAP "method" names have tended to be in camelCase because that is the convention in the languages that some of the earliest published services were made in (e.g. Java .) Of course this only really matters if you are using "rpc/encoded" envelopes rather than "document/literal" but you probably want to consider what the toolkit is going to do with the method name in framing the response - if you go with the lower case underscore separated names you are likely to have a body payload with an element name of something like: my_perl_method_nameResponse which is the worst of both worlds and horrible IMO, however this is going to be of concern if people are examining the Envelope or the WSDL manually. Personally nowadays I would tend to think of web services in terms of the message-centric document/literal style rather than the method-centric (and therefore less implementation neutral) rpc/encoded in which case the design and naming issue becomes one of what is most appropriate for the XML documents that are being exchanged.
/J\
