Zemlin also reiterated the stance of the foundation and the general open-source community that patent-infringement cases "only burden the software industry and do not serve their customers’ best interests."

"Instead of litigating, we believe customers prefer software companies to focus on building innovative products," he wrote.

Andrew Updegrove, an IP lawyer with Boston-based law firm Gesmer Updegrove and an outspoken critic of Microsoft's IP policies, said via e-mail Thursday he believes Microsoft is sincere about the suit being a "one-shot move against TomTom." Updegrove also posted about the suit on his .

Still, he thinks the suit is consistent with Microsoft's historic flip-flopping over open source and Linux in particular -- on one hand saying it wants to work with the community, on the other hand dangling the threat of patent litigation.

"Net result? Nothing new," Updegrove said. "Lumping the Linux claims [in the suite] is an opportunistic move to reignite fear in the Linux space" that eliminates "any incipient trust they might have been building, once again, in the open-source community," he said.