Michael Kay (XML guru, editor the XSLT 2.0 specification, and author of Saxon an excellent XSLT and XQuery processor), published an article on using XML technologies to build workflow applications. He describes workflow applications as "applications that one can think of in terms of documents moving around a community of people who each perform particular tasks". He explains why XML and standard XML technologies like XSLT, XQuery, XML Schema, or XForms, are a very good fit to implement workflow applications. He also has some nice words for our product, PresentationServer:
[...] There are various tools you could use in this role, but most of them are completely general-purpose. I would recommend instead that you consider an approach that specialized for handling XML. An example that I have used very successfully is the Orbeon PresentationServer (www.orbeon.com).
In 2003, we published an article where we were making a very similar point: while most people still design applications around data models and operations, your architecture becomes simpler when you think in terms of documents and processes. Documents are in XML, and XML standards provide all the tools to process those documents, for instance: XForms to capture data with forms, XML databases to store it, XQuery to extract information, XSLT to transform XML into HTML.