Among other things, the W3C is now looking to develop new standards for rich user interface applications. To quote,
The W3C Web Application Formats Working Group is chartered to develop languages for client-side Web Application development.
This deliverable should be based on an existing application/UI format, such as Mozilla’s XUL, Microsoft’s XAML, Macromedia’s MXML or Laszlo Systems’ LZX, provided the owners of the format are willing to contribute. The format should allow embedded program code. This format, combined with the deliverables below and existing technologies including XHTML, CSS, XForms, SVG and SMIL, should provide a strong basis for rich client application development.
Interesting. To me, XUL is pretty much the most standard standard out there, although it leaves a bit to be desired and it’s far from widely recognized – there’s a lot more markup-based user interface languages, as well as proprietary formats such as Macromedia’s MXML and Microsoft’s XAML.
I don’t think any of these companies would drop support to their own formats and embrace a new W3C standard (unfortunately), but I think actually having a W3C-sanctioned standard will really help UI development in the future – if anything, for independent applications and projects.
Personally, I’d love seeing a game engine supporting a subset of the XUL features – saving us the madness of crazy proprietary tagging such as Doom 3’s GUI system or the crazy Java-like coding and compiling of hardcoded interface widgets such as UnrealTournament’s Gui classes. In the long term, this step might help a bit in that direction. I’ll have to keep an eye on this.