This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
XML-RPC is a more light-weight protocol for making RPC calls using XML over HTTP. Web services is heavier but also more rich in functionality (there's plenty of WS- prefixed specifications coming our way...).