As if there wasn't enough new client-side technique to cover, what with Ajax, DHTML, CSS and so on, there's also XForms -- the next-gen, XML-based, MVC-based, portable answer to HTML forms. They were made an official W3C recommendation back in March, they work in IE and Firefox, and they could very well become part of the Web 2.0 toolkit. Get the skinny at the first of a three-part series at IBM's developerWorks in an article titled Introduction to XForms, Part 1.