IBM's Action is very interesting: not only are patents made freely available to free software, but there is also a clear declaration of war against litigious parties. Anyone who pursues lawsuits against Open Source runs the risk of losing the rights to use IBM patents. Of course, it's now interesting to see exactly which patents IBM is making available, but I could well imagine that IBM has some real blockbusters in there. After all, IBM is one of the companies with the largest patent portfolio (if not the company with the largest one).