A talk by Paul Graham at Google about whether software patents are evil. One concern he has is whether in a world where patents are legal firms should patent things. Like Graham I would have a hard time advising anyone not to take advantage of the law as it exists - especially since if you don't take out defensive patents you are a potential victim. The talk is hardly a ringing endorsement of patents as a matter of public policy, though. First, he provides some insight into what sort of companies file patent lawsuits (as opposed to filing patents)

A company that sues competitors for patent infringement is like a a defender who has been beaten so thoroughly that he turns to plead with the referee. You don't do that if you can still reach the ball, even if you genuinely believe you've been fouled. So a company threatening patent suits is a company in trouble.

When we were working on Viaweb, a bigger company in the e-commerce business was granted a patent on online ordering, or something like that. I got a call from a VP there asking if we'd like to license it. I replied that I thought the patent was completely bogus, and would never hold up in court. "Ok," he replied. "So, are you guys hiring?"

The main case against patents is that they don't work terribly well in encouraging innovation - the reason for having them in the first place. Graham apparently agrees

In the software business I know from experience whether patents encourage or discourage innovation, and the answer is the type that people who like to argue about public policy least like to hear: they don't affect innovation much, one way or the other. Most innovation in the software business happens in startups, and startups should simply ignore other companies' patents. At least, that's what we advise, and we bet money on that advice.