News.com reports that a company called Acacia is beginning a systematic legal campaign to enforce its patent on--wait for it--"the process of transmitting compressed audio or video online." In other words, a large proportion of Internet activity.
Acacia is no lightweight: they spent an enormous amount of time researching the legal enforceability of their patents before sending out their letters.
People and companies are responding to these legal threats with capitulation. Even the big players are cowed: Radio Free Virgin, the online music division of the Virgin corporation, has signed a license with Acacia. It's not hard to see why: the high cost of litigating a patent infringement lawsuit means that it's cheaper for companies to buy a license, however unjustified, than to go to court.