The Mozilla Project has posted version 0.8 of
its XForms extension for 
 Firefox 1.5 and later.  Mozilla XForms support has been
developed  by IBM, Novell, and
independent contributors.  Improvements in this release include
SOAPAction on submission,  mediatype on output elements,
range support for many different datatypes,
resource element and attribute for submission. It's not a complete XForms implementation yet, but it's getting there.