It's time we faced it: The Year of the Linux Desktop, long foretold, isn't coming.

Year after year, breathless pundits announce that the open source OS is on the verge of a tipping point, a critical mass that will see businesses abandoning Windows in droves. And year after year, nothing happens. Is it too late for desktop Linux to matter?

[ See why desktop Linux makes a better successor to Windows XP for most business users than Windows Vista or 7 -- if only businesses would give it a chance. ]

The issue isn't whether Linux is "ready for prime time." Modern desktop-centric Linux distributions -- including Mandriva, Novell Suse, Ubuntu, and Xandros -- have made impressive strides in aesthetics, usability, management, and hardware support. Major hardware manufacturers ship systems with Linux pre-installed, and Dell reports that customer satisfaction rates are just as high for the Linux models of its Inspiron Mini 9 netbooks as for the Windows models. Today's Linux really is reliable, polished, and full-featured enough for mainstream desktop use.

Even Microsoft admits it. After years of denial, the software giant's latest SEC filings acknowledge mounting competitive pressure from Linux, and not just in the datacenter. Addressing Microsoft investors in February, CEO Steve Ballmer went as far as to suggest that the open source OS could be a greater threat to Windows than Mac OS X. That same month, Microsoft began actively recruiting a director of open source desktop strategy, a position whose responsibilities will include "influencing multimillion dollar marketing campaigns."

Enterprises aren't buying the Linux promise, nor are vendors Yet if Microsoft is willing to spend millions on desktop Linux, the enterprise plainly is not. Even given the backlash against Vista and uncertainty surrounding Windows 7, there has been no mass exodus. By Ballmer's own figures, the greatest threat to Windows remains unlicensed Windows, not Linux. In fact, according to research from Net Applications, Linux's market share has declined in recent months, despite the breakout success of low-cost Linux netbooks.

Meanwhile, leading Linux vendor Red Hat has "no plans" to deliver a mainstream desktop Linux distribution. At the recent Open Source Business Conference, Red Hat CEO Jim Whitehurst admitted that he doesn't know how to make money on it. And even Novell, which markets a commercial desktop Linux distribution aimed at enterprise customers, says building a market for the OS among consumers will take years.

If major Linux vendors aren't ready to put their full faith behind Linux on the desktop, who will? More importantly, what will it take for Linux to overcome the barriers to mainstream acceptance and realize its full potential -- if it's even possible?