This i sprobably it, where so much recent software developemnt has been heading. Just as we're getting used to server driven web services along come client driven web services.
Our current approach to most development is to write everything server side, let the server call on other web services (speech systems, maps, google and amazon databases etc), and then let the server serve the finished page out to the relevant device in the relevant mark-up, HTML, Sitepal HTML for web speech, VXML for phone speech, WAP etc.
What differentiates this from old style client-server is that the client page is usually served from the server. So for instance the server core might handle initial sign on and a top level menu. Then each main application area gets its own AJAX page which can be served out to the user and take-over until they need another key bit of the application. Once we've got our GoogleMaps demo out the way we'll see about doing an AJAX demo.
***Imported from old blog***