The more I think about it, the more interesting the comparison becomes. The difference in approach is that the patent system assumes that people will only disclose their inventions for an incentive - a 20 year monopoly over the exploitation of the invention.

This "you don't get something for nothing" approach seems fairly true of human character. So what of the Open Source model? Pure altruism might motivate some (like Richard Stallman), and the hero factor, kudos and the like might motivate others, but I don't think that we've covered the field yet.

Maybe it's just pure love of technology. The prevalence of science fiction lovers in geek circles might hold true of that. Perhaps they see things like Microsoft bullshit, SCO v UNIX,  Amazon's one-click patent et al and see this as halting the progress of technological innovation. I must admit that there is a certain rush to be had out of seeing new technologies hit the mainstream.

I don't really have the answers - I'm still thinking it all through - but it makes for interesting reading.

Another interesting difference between the patent system is in the extent of disclosure. Not only does open source software allow immediate access to the specifications (IP-speak for the instructions on how to best perform the invention), you also get the full working implementation. Take for example Microsoft's patent over the .NET Framework. In 20 years, all you get is the patent document with instructions on how to create the .NET Framework. You could then start implementing it without fear of a lawsuit, but as the Mono Project illustrates, this is more than a day's work.

So to sum up, I think I know which system I prefer. Hope I've given someone a few things to think about :)