Red Hat recently issued a press release under the title What's Going On With Red Hat Desktop Systems? An Update whose content boiled down to "It's a loser, so We're bailing."
Novell's SUSE Linux Enterprise Desktop 10 is a cool two year old product from a company whose CEO recently opined that the Linux "consumer desktop will take years".
Ubantu has lots of vocal support but isn't expanding its base; there's no new Debian in sight; and the excitement that could drive one of the other distributions into the spotlight just doesn't seem to be there. Even the Linux based OLPC, a product whose interface could have been a threat to Windows, seems to have been successfully embraced, extended, and extinguished.
So what happened? Where did the Wintel discontents -the people exposed to Vista without the commitment focusing benefit of having their jobs and self-images depend on selling Microsoft - go?
Since there's no hardware differentiation between Wintel, Lintel, and Mactel I think what's going on is that people knowledgeable enough to look for alternatives to Windows are comparing the Linux desktop to MacOS X and choosing MacOS X. If so, that would be why Vista hasn't done much damage to Windows sales, but Linux desktop momentum is essentially gone while Mactel sales continue to rise.
Look at stuff like this bit from a March 26/08 Computerworld story by Gregg Keizer and you can see the obvious reason why:
Corporate users of Apple Inc.'s Leopard operating system are more than five times more likely to say that they are "very satisfied" with the OS than business users of Microsoft Corp.'s Windows Vista, a research firm said Wednesday.
In a February survey of 2,200 U.S. corporate computer users, 53% of those using Mac OS X 10.5 reported that they were very satisfied with their operating system. Of those using Windows XP or Windows Vista, however, 40% of the former and only 8% of the latter said they were very satisfied.
There is a more subtle reason too: I think people who compare the Linux desktop, especially the Gnome incarnations, to Windows tend to see Linux as imitative while those who compare Windows Vista to MacOS X cannot but see Windows as imitative - and, given a choice, people will take the real thing over an imitation every time.