Mark Shuttleworth, the founder of Ubuntu, wrote an article about Microsoft:
But let’s step back from the coal-face for a second. I have high regard for Microsoft. They produce some amazing software, and they made software much cheaper than it ever was before they were around. Many people at Microsoft are motivated by a similar ideal to one we have in Ubuntu: to empower people for the digital era. Of course, we differ widely on many aspects of the implementation of that ideal, but my point is that Microsoft is actually committed to the same game that we free software people are committed to: building things which people use every day.
So, Microsoft is not the real patent threat to Linux. The real threat to Linux is the same as the real threat to Microsoft, and that is a patent suit from a person or company that is NOT actually building software, but has filed patents on ideas that the GNU project and Microsoft are equally likely to be implementing.