In case you haven’t heard of or seen XULRunner (pronounces ZoolRunner) it is pretty slick stuff. FireFox 3 is scheduled to be a 100% XUL based application. You can check out the roadmap where it shows FireFox 3 will ship in Q1 2007 and based on XULRunner 1.9.
|XULRunner is a Mozilla runtime package that can be used to bootstrap XUL+XPCOM applications that are as rich as Firefox and Thunderbird. It will provide mechanisms for installing, upgrading, and uninstalling these applications. XULRunner will also provide libxul, a solution which allows the embedding of Mozilla technologies in other projects and products.|