From Todd Bishop's Seattle PI Microsoft Blog... Microsoft's lawyer on why they will not disclose which patents they believe Linux violates...
That is not something that any other company in our industry does today. And yet, we do find ourselves as a company repeatedly getting requests from other companies to license their patents, to pay them royalties. We believe that, especially as long as there are other companies in our industry that come to us, asking us to take a license and pay a royalty, that it is important for us to work on a reciprocal basis -- and that means providing information on our patents in a forum where they are providing information to us on their patents. We're not comfortable being the only company in our industry, certainly, to take a unilateral step, especially when that step could change the dynamic, subsequently, for discussions with other companies.Software patent portfolios are for intimidation, silly. The murkier the better.