I’m giving a free Webinar on 15 April 2008 9-10AM PDT about the approach we took to service composition in the WSO2 SOA Platform.  Instead of a declarative approach which my XSLT days showed can be powerful yet also limiting in many ways compared with a full programming language, the WSO2 Mashup Server uses a "scriptable Web Services" metaphor, and supports the ability to consume and produce Web Services using simple Javascript expressions.  Add to that the ability to script non-Web Service materials like Web pages and feeds, and you’ve got a powerful yet accessible platform for creating Web Service mashups.  Register now!