Dave Winer has an interesting take on this issue.
According to him, you should give away software when you want competition, and keep it when you want to compete. I can understand where he’s coming from. Don’t get me wrong, I love the idea of open source software (I’ve written a bit myself, including the software that runs this website…. it’ll be open soon :-). But at the same time, I’m a software developer that gets paid to do what I do, and I’d be rather upset if I couldn’t make a living doing it.