Microsoft claims that free software like Linux, which runs a big chunk of corporate America, violates 235 of its patents. It wants royalties from distributors and users. Users like you, maybe. Fortune's Roger Parloff reports.

CNN reports:
Caught in the middle are big corporate Linux users like Wal-Mart, AIG, and Goldman Sachs. Free-worlders said that if Microsoft prevails, the whole quirky ecosystem that produced Linux and other free and open-source software (FOSS) will be undermined.

Microsoft counters that it is a matter of principle. "We live in a world where we honor, and support the honoring of, intellectual property," says Ballmer in an interview. FOSS patrons are going to have to "play by the same rules as the rest of the business," he insists. "What's fair is fair."

Microsoft General Counsel Brad Smith and licensing chief Horacio Gutierrez sat down with Fortune recently to map out their strategy for getting FOSS users to pay royalties. Revealing the precise figure for the first time, they state that FOSS infringes on no fewer than 235 Microsoft patents.

It's a breathtaking number. (By comparison, for instance, Verizon's (Charts, Fortune 500) patent suit against Vonage (Charts), which now threatens to bankrupt the latter, was based on just seven patents, of which only three were found to be infringing.) "This is not a case of some accidental, unknowing infringement," Gutierrez asserts. "There is an overwhelming number of patents being infringed."

The free world appears to be uncowed by Microsoft's claims. Its master legal strategist is Eben Moglen, longtime counsel to the Free Software Foundation and the head of the Software Freedom Law Center.

Moglen's hand got stronger just last month when the Supreme Court stated in a unanimous opinion that patents have been issued too readily for the past two decades, and lots are probably invalid. For a variety of technical reasons, many dispassionate