The original W3C Note has SOAP as an acronym for Simple Object Access Protocol. Afterall, it was designed as an RPC protocol to invoke methods on objects.
The W3C Recommendation specifically states that SOAP 1.2 will not spell out the acronym. The reasoning was that object method invocation is only a secondary use, the primary being packaging XML documents that can be sent in any manner possible. Actually W3C started with XMLP (for XML Protocol) as the name for the protocol but accepted the term SOAP anyway.
Today, while browsing the Web, I came across this article that suggested SOAP for SOA Protocol. The same article also mentions that exposing object level access is against the SOA principles.
Works for me.