I was pointed to this post by "mnot" via Christian Weyer's blog on whether SOAP is a protocol or a format. To be honest once I really got my head around SOAP I started thinking of it as a message format. That was around the time they really stopped calling it "Simple Object Access Protocol", and just called it SOAP. It deemphasised the object part for most, but it also deemphasised the protocol part for me.

An interesting read.