In 2007, much of the open-source action happened outside the corridors of the usual corporate suspects.

For years, the center of open-source software, at least from a commercial perspective, was with companies such as Red Hat, Novell, MySQL, and a number of smaller players. Those companies continued grinding away at their collaborative programming projects and support-centric businesses, but more unusual for the year were the new arrivals.

Adobe Systems was one. It's long been a powerful proprietary-software company, but its acquisition of Macromedia led to a new sharing ethos. Shortly after a major donation of script-execution code to the Mozilla Foundation last year, Adobe announced in April the open-source release of its Flex tool for Flash programming.

Another convert is Yahoo, which bought open-source e-mail firm Zimbra in September for $350 million and made its Flickr Uploadr tool open-source software in December. More expensive than Zimbra was Citrix's $500 million buy of open-source virtualization company XenSource.

Perhaps the most unusual open-source move was from Microsoft. Chief Executive Steve Ballmer engaged in some high-profile saber rattling by asserting that Linux, OpenOffice.org, and other open-source packages violated 235 Microsoft patents. But at the same time, the company sought and received the official "open source" imprimatur on two Microsoft software licenses.

A far more significant license arrived in June: version 3 of the General Public License, which after fractious debate emerged with new requirements regarding patent grants and use of free software in consumer products.

One of the biggest new arrivals in the open-source scene is Google. Two examples in 2007 are a significant contribution to the MySQL database project and the Google Gears project for online Web applications. Most visible was the Android mobile-phone software, which emerged with much hullaballoo in November.

Sun Microsystems has embraced open-source software as a way to engage tech-savvy customers. After years of reluctance, the open-source Java deed was done with the release of the OpenJDK project at the JavaOne trade show in May. Longtime Java holdout Red Hat cheered the move and agreed to help code over remaining proprietary patches.

Sun also hired a longtime Linux expert, Ian Murdock, to transform its OpenSolaris project from a bundle of bits into a workable operating system that people could use--in effect adopting the Linux distribution approach. The first fruits of "Project Indiana," though only a test version, emerged in November.

That's mostly obscure server software, though. Many more are familiar with the Firefox Web browser, one of the highest-profile open-source projects. The Mozilla Corp. overseeing the effort had hoped to ship the first Firefox 3 beta had been due to ship in July, but in fact it arrived in November.

Firefox continues to be a strong runner-up to Microsoft Internet Explorer in Web usage. And Mozilla's finances continue to grow--chiefly from Google, which pays for promotional placement such as the default start page. Mozilla revealed in October that its revenue in 2006 was $66.8 million, about 85 percent of it from Google.

With the money, Mozilla will hire more programmers to create a mobile version of Firefox, among other things. Another investment: the Mozilla Foundation that oversees a Firefox subsidiary also said it will fund a comparable subsidiary for improving the Thunderbird e-mail software. The general idea is to create software that can handle not just a main e-mail inbox but also text messages, instant messages, and missives on Internet services such as Facebook.