FORTUNE — An alliance of technology corporations, including IBM, is expanding the scope of patent protection it provides to developers, vendors, and users of open source software such as Linux. The move cuts against the grain of major companies going after each other, filing suit over patent infringement.

The consortium, known as the Open Invention Network, already provides an array of patent protections to certain Linux and open-source applications found on corporate data-center and back-office servers. Today’s announcement will extend those protections to more than 700 additional open-source software packages, including Android, Google’s (GOOG) smartphone operating system; OpenJDK, a popular programmers’ development kit; and applications relating to network management and security. “As the Linux community expands,” says the network’s CEO Keith Bergelt, “we’ve had to broaden the aperture of our protections.”

OIN was formed in 2005 by IBM (IBM), Novel, Philips, Red Hat, Sony (SNE), and NEC (NIPNF) to foster a cooperative environment in which free and open-source software (FOSS) could thrive. Today the OIN’s original charter members form the hub of a community that includes more than 400 “licensee” companies, including such giants as Google, Oracle (ORCL), Yahoo (YHOO), Fujitsu (FJTSY), LG Electronics (LGL), and, as of the past year, recent signatories like Facebook, Twitter, and Cisco (CSCO).

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Free and open-source software is written collaboratively by independent programmers and, by its licensing terms, confers certain “freedoms” upon users that are usually forbidden by proprietary software companies, like Microsoft (MSFT). These freedoms include the right to see the software’s source code, alter it, copy it, and redistribute it. The best known open-source product is Linux, or GNU/Linux, a complete open-source operating system that quickly became popular among Fortune 500 corporations for use on data-center servers. Patents threaten the free-and-open-source eco-system, however, in that none of the key open-source freedoms can be practiced if an outsider can establish that a given piece of software infringes a valid patent he holds.

OIN has, therefore, acquired a defensive portfolio of strategic patents which it makes available, royalty free, to companies that commit not to assert their own patents against members of the Linux community. Every licensee also then enjoys royalty-free protection from every other licensee’s patent portfolio, at least as it relates to the specific Linux applications that are designated in the license. Today, the licensees’ collective portfolio includes more than 350,000 patents and applications.

Because OIN’s original definition of Linux no longer reflects the breadth of Linux’s actual usage, OIN is expanding that definition. As a result of the change, for instance, Linux-based Android—today the leading smartphone operating system—will become covered by the OIN definition. (According to the comScore metrics service, Android had 47.3% market share as of December. Apple (AAPL) was second, with 29.6%.)

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Bergelt is optimistic, he adds, that additional companies will be signing OIN licenses at an accelerating pace within the next year or two, and that these new members might include, for instance, Samsung, Intel (INTC), Huawei, and Dell (DELL), which are “all making major investments in Linux and open source.” He suggests that at some point the network will reach a tipping point at which companies that have not joined up may feel increasingly isolated. “You work with people you’re comfortable with,” he says. “If you’re not a licensee, you might be seen as not committed to Linux or open source.”