Sun is entering the XML for UI game with JDNC. They will make it open source this fall on javadesktop.org.

Raible and the XUL announce mailing list seem to think XUL will be more successful.

Personally I really like XUL's ease of layout but I'm waiting for a few things. The Gecko Runtime Environment has to mature. Gecko is what you need to render a XUL GUI so it's important. I'm not even sure of its status at this point but the recent change in the Mozilla development roadmap will probably give more focus to the GRE. Gecko's memory footprint also needs to improve.

What I'm really waiting for is the Javascript to Java interface for XUL. XUL-based GUIs use Javascript to communicate with the actual application code that does the grunt work. In Mozilla, this is done with XPCOM and C++. I should be able to make Java calls cleanly from JavaScript -- none of this COM garbage. As soon as that happens I'll be playing with XUL for sure.

So what happens to SWT? Maybe the best of the layout advantages from XUL and the JFace conveniences from SWT can combine somehow. All I know is that XUL is far far easier to layout GUIs with.

Maybe the Eclipse team can write SWT in JavaScript. ;) Heh, it's probably more likely that the Gecko Runtime Environment team would add support to write in Java instead of JavaScript in XUL code. Now that would be interesting.