The FT (Wednesday, 25th April) had a profile of Nathan Myhrvold, a former Microsoft exec, who set up a company Intellectual Ventures, essentially for patent trolling. Here is one article and one video on what he is doing.
Following up from my earlier post defending patent trolls, there is a sense in which Myhrvold sees himself as providing liquidity in markets for ideas; especially as he employs people to generate patentable ideas.
But he also buying up patents of failed start-ups too. This situation can only be favourable to innovation: start-ups who can earn a little money even if they fail are more likely to attract investment funds in the first place. And the more patent trolls there are, the more that avenue for profits can work out in the innovator's favour.