Microsoft is now on a public relations offensive about open source and patent law, with the company's general counsel claiming in a Fortune article that open source software infringes upon at least 235 Microsoft patents, with 107 accounted for by the Linux kernel and graphical user interface alone. But is Microsoft still just blowing hot air?Their philosophies at odds, Microsoft and the world of open source, especially Linux, have been on the precipice of a much larger clash for years. See Microsoft's now notorious total cost of ownership comparisons, for example. Or statements by Microsoft executives that Linux is this era's great threat to the company. Over the weekend, though, thinly veiled threats have boiled over into a more specific (if still not specific enough) barrage of complaints.

Already, the Microsoft-Novell deal of last year (which now includes Dell) had mucked up the water by inferring that Microsoft could sue businesses using Linux if they weren't Novell customers. Well, actually, the deal didn't say that, but it said Microsoft wouldn't sue Novell Linux customers a la the recording industry and people downloading the latest Justin Timberlake album.

Meanwhile, I've gotten an e-mail from Microsoft's public relations agency offering up an interview with "someone" at Microsoft in regards to the topic (I'm going to take them up on the offer). So this is clearly an issue Microsoft now wants out there. The Fortune article, which quoted an interview my colleague Charles Babcock did with Linus Torvalds, wasn't a fluke.

But what is Microsoft even really doing at this point? Not much. And what can it? Maybe it can sue Red Hat, or Richard Stallman, or a whole host of non-Novell Linux users.

Regardless, those avenues may be closing a tad. The Free Software Foundation responded to the Novell deal by including wording in the new general public license that, as Fortune puts it, "if Microsoft continued to issue Novell Linux coupons [part of a marketing collaboration] after the revised GPL took effect, it would be waiving its right to bring patent suits not just against Novell customers, but against all Linux users." Ouch, but I wonder how well that would hold up in court, and the same PR e-mail mentioned above raises a specter of uncertainty over GPL3. Still, the Linux Foundation has strengthened its legal chops. Red Hat has apparently turned down a deal like Novell did with Microsoft. The Supreme Court, meanwhile, which has never really said whether software is patentable, recently said something to the effect that patents have been ruled too willy-nilly anyway in recent years. And Congress is on the hunt to rewrite a wide swath of patent law. Plus, there's that weensy little company, IBM, which loves open source.

For now, though, the most to do is continue to say "we'll see." Microsoft is still continuing to say things without putting court filings where its mouth is.