Microsoft has filed suit against GPS maker TomTom in the U.S. District Court for the Western District of Washington and before the International Trade Commission, according to LinuxInsider.com. Microsoft says TomTom has violated eight of its patents.

Two things about the situation are noteworthy: First, Microsoft has only filed patent lawsuits twice before in its history. As LinuxInsider.com writer Erika Morphy points out, "Prior to the TomTom filing, Microsoft had initiated lawsuits against just two firms -- Primax and Belkin -- both of which were settled." The company defends patent suits almost constantly, but files them hardly at all.

Second, three of the claims at issue deal with TomTom's implementation of the Linux operating system. As such, some in the Linux community are up in arms. Glyn Moody, for instance, thinks Microsoft's concern for its patents is finally overriding the newfound respect it has been exhibiting toward Linux and other open source programs, and this is the beginning of an all out "patent war."

Others are taking a wait-and-see approach. Linux Foundation Executive Director Jim Zemlin summed it up in three sentences: Calm down. Hope for the best. Prepare for the worst. He says simply, "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." But if -- and that's a big if in Zemlin's estimation -- Microsoft does come calling, the Linux Foundation and its partners will be ready.

Stephen Walli says the case is not about Linux or open source at all. It's about the mobile Internet:

The world is changing rapidly since Apple demonstrated what the mobile Internet can look like with the release of the iPhone. There has been a rush of delivering iPhone competitors to market since then... There are considerably more handset devices on the planet than PCs. This feels like a much bigger fight than the first shots in a Linux patent fight.