InfoQ: XUL: What the web should look like?
Ten years ago it was considered acceptable to have isolated platforms and programming languages that didn’t interact with other platforms. These days, that is no longer tolerated. To wit, XPCOM and XPConnect are offered.
Another hot topic these days is internationalization. XUL has that covered by storing human readable text in DTD and property files. In what will surely make translation easier, these files can be created and packaged separately from the XUL code itself.
Unlike many open source projects, tool support is not lacking either. The XUL homepage lists several tools and utilities including XUL Explorer, a lightweight IDE.
At first glance it may appear that XUL has the same problems as Gran Paradiso, namely being tied to the Mozilla family of browsers. However, that isn’t the case. Another Mozilla product, XULRunner, allows XUL based applications to run outside the browser. Currently it is available for Windows, OS X, and Linux.