The SCO Group's high-profile legal actions targeting Linux faded from prominence in 2004, but they left a legacy: scrutiny of the intellectual-property foundations of open-source software.

SCO surprised the computing industry in 2003 with a lawsuit against IBM that argued Linux wrongly contained Unix technology. In 2004, the company fulfilled a pledge to sue Linux users, targeting AutoZone and DaimlerChrysler. But the legal case has lost urgency: Most of the DaimlerChrysler suit was thrown out, the IBM case has entered a legal maze of testimony and obscure motions, and the AutoZone case awaits rulings from other SCO cases.

Yet there have been other repercussions. Various offers of legal protections sprung up from Linux sellers Novell and Red Hat, while start-ups Open Source Risk Management and Black Duck Software hope to capitalize on legal worries. Meanwhile, IBM pledged not to use its mighty patent arsenal against Linux.

With SCO's star waning, others stepped in to rile Linux loyalists. Conspiracy theorists pounced on the news that Linux rival Microsoft had played matchmaker with SCO and BayStar Capital, which helped arrange $50 million in crucial funding for SCO. Microsoft Chief Executive Steve Ballmer fueled the flames by drawing attention to a study arguing Linux could infringe 283 patents.

And Sun Microsystems launched a direct attack on Red Hat with its Solaris version of Unix. Red Hat fought back with criticisms that Sun refuses to make Java open-source software. A new twist in the rivalry: Sun plans to release Solaris as open-source software by early 2005.

Linux, meanwhile, continues to become a staple of the computing diet. Linux server sales surpassed $1 billion in the third quarter of 2004 and should reach $9.1 billion for 2008, according to IDC. The two fastest supercomputers both run Linux. Novell and Red Hat have become more aggressive with desktop versions of Linux.

Open-source software continued its spread elsewhere, too. Hewlett-Packard signed deals to use JBoss' open-source application server, which runs Java programs on servers, and Sendmail's e-mail software. Analysts expect database software from MySQL to gain ground on proprietary rivals. SugarCRM is gunning for the lucrative customer relationship management software category. And the Firefox Web browser, the product of one of the earliest efforts to commercialize open-source software, has dented the dominance of Internet Explorer.

Some of the most telling examples of the powers of the cooperative programming movement come from its foes. Microsoft is getting involved in open-source software. Tight Microsoft ally Unisys had a change of heart, signing Linux deals with Red Hat and Novell. Even SCO, which has called the General Public License, or GPL, that governs Linux unconstitutional, relies on other GPL software packages for its Unix software.

--Stephen Shankland