Erik Arvidsson, the DHTML guru behind WebBoard and WebFX, revealed what he had been working on since last year: Bindows.  Bindows is a DHTML framework that emulates Swing/WinForms UI, similar to what Convea and Oddpost.  I am not sure yet, but Bindows seems to use XML to define its GUI.  It seems pretty slow though.  I suspect that most, but not all, of the slow speed is due to the server-side misdesigns.