If you haven't heard of Intellectual Ventures, you will do. Set up by ex-Microsoftie Nathan Myhrvold, with investments from Microsoft among others, it is basically a patenting machine – filing and buying them in huge quantities. Note that it doesn't actually *use* these patents – except to threaten people with. In other words, Intellectual Ventures is a patent troll – or, rather the King of the Patent Trolls.
On Open Enterprise blog.