I'm not entirely sure how this got modded insightful. The patent system is certainly not built upon owning an idea. They cover a particular implementation, a certain solution to a problem, not just an idea. If you invent a machine that makes unicorn farts, you can patent that machine. If I make a unicorn fart machine that operates in a different way, I am free to do so. Now the market has two different unicorn fart machine styles, and we are arguably better off as a society.
As an engineer with some hands on experience filing and working around patents, I can honestly say that a large part of the patent system still works as intended. I believe inventors should be protected, especially when it's a David and Goliath situation, and patents still offer some of that protection. I also believe that the patent system encourages inventors in at least two ways. It lets you know that there is at least one solution to your problem, and that somebody thought it was worthwhile enough to patent it. It also forces an inventor to be more creative and come up with different solutions to the problem than what has already been done. Sometimes when you have to think of a different solution, you end up with a better solution.
That being said, I think business method patents are stupid, and that software patents are evil. And if you're going to file a patent on something, you sure as shit better not try to sue me on "trade secret" grounds. (yes, that actually happens)