Microsoft has long claimed that Linux violates its patents, but has refused to be specific. A recent deal between the software company and a printer maker may offer a clue.

Earlier this week, Microsoft announced a patent cross-licensing agreement with Japan's Kyocera Mita.

Under the deal, Microsoft gets to add patented Kyocera Mita technology to its Windows and Office products.

What does Kyocera get? The right to use patented Microsoft technology in its printers, copiers and "certain Linux-based embedded devices."

The question, of course, is why Kyocera Mita would need a patent from Microsoft to enhance products built on embedded Linux. Is it adding proprietary Microsoft technology on top of embedded Linux?

Could be…

Or is this a case of Kyocera Mita accepting a claim by Microsoft that embedded Linux is among the 235 open source technologies Microsoft insists it owns.

Microsoft says the deal "delivers on our promise to continue to build a bridge between open source and proprietary software and technologies."

Hard to know what that means--it's deliberately vague. As for other aspects of the deal…"The terms of the agreement are not being disclosed," says Microsoft.

But did they already tip their hand?