[naner]

As far as I can tell, Microsoft claims they have patents that cover technologies/algorithms in the Linux kernel. I've never heard them get more specific than that. They approach companies and request them to pay a licensing agreement (or come to a cross-licensing agreement if the company has patents they can use against MS). TomTom disregarded the threats and got sued over Fat32. I imagine Microsoft's patent portfolio is vast enough to find something that will stick most of the time so the threats aren't completely unfounded.

Here's a brief article on the Amazon licensing agreement:

http://www.zdnet.com/blog/microsoft/amazon-becomes-the-lates...