But if Microsoft wants a fight -- oh boy, is the open-source community ready for it.

First, it should be noted that Microsoft is claiming its lawsuit, made public this week, isn't really about Linux or open source. Horacio Gutierrez, Microsoft's corporate vice president and deputy general counsel of intellectual property and licensing, said that while "three of the infringed patents implicate open-source code ... open-source software is not the focal point of this action."

Nonetheless, Andrew Updegrove, a partner at Boston law firm Gesmer Updegrove LLP is concerned that Microsoft has been getting more aggressive about approaching companies and their use of Linux. "I've received e-mail in the past from people that Microsoft has approached, alleging Linux infringement and saying 'You better get a license from us, or else,'" Updegrove said.

On the other hand, moving aggressively against Linux "doesn't make sense to me, because I can't think of any reason why they should move now and several reasons why they should not: the [European Union] is still on their tail regarding browsers (and Gooble [sic] just joined in against them), and there's a new administration in town in Washington -- why test them at this point in time, rather than lie low and watch for awhile and see whether antitrust enforcement is back in town?"

Updegrove isn't the only one who's puzzled by Microsoft's move. Eben Moglen, a Columbia University law professor and co-author of the primary open-source license -- the General Public License, Version 3 (GPLv3), called it "a little mystifying. The FAT (File Allocation Table) patents aren't the strongest ammo in anyone's gun. This will do harm to their free-software co-existence process, which has had some viability. This will harm Microsoft credibility with free software.

"My job is to keep the community safe from aggression," Moglen said. "We need peace and that implies co-existence."

And if Microsoft wants to make a fight of it? "I'm sure that all free software parties, both community and corporate, will join together to formulate a measured, united response," added Moglen.

That's exactly what the Linux Foundation and the Open Invention Network seem to be doing. Jim Zemlin, the Linux Foundation's executive director, wrote in a public blog: "Right now, the Microsoft claim against TomTom is a private dispute between those two entities concerning GPS mapping software. We do not feel assumptions should be made about the scope or facts of this case and its inclusion, if any, of Linux-related technology."