Firefox has never looked or felt like a native application on the Mac. It didn't even have native form controls or pixel-perfect scrolling ala Safari until fairly recently.

I've heard of in-house apps being done with XUL. I'm not aware of any used by the general public, other than Firefox.

To be a successful cross-platform development environment, there would have to be lots of these. To my knowledge, only web apps are that widespread and used by the general public, not primarily for in-house apps.

... and is slow, pillages your RAM, and for many folks is a de facto web IDE. :) Think Firebug, etc.

There don't seem to be many. But I believe it has been used quite extensively in internally-developed applications, never intended for the mass market. The same goes for Swing as well.

So although end consumers might not see them, it will certainly take a long time for SWT or Swing to die. These are the same class of applications that are keeping IE 6 alive, after all.

Does this matter to Apple? I doubt it's significant, as most of these applications are probably running on Windows desktops already. Probably more significant is the legion of Java developers that have been vocal proponents of Macs over recent years. The numbers of such developers might not be so great in an absolute sense, but the amount of noise they create is disproportionate. And, more importantly, they are more motivated to build interesting stuff for the platform they use.

Lotus Notes and Lotus Symphony aren't consumer apps but they both have a pretty big user base beyond typical Eclipse users. Azureus is the first consumer app that comes to mind.

Azureus (Vuze) is one of the most popular bittorrent clients.

JDownloader bundles the SWT libraries, but I don't know how much of its UI is written in SWT.