For the moment, I'll just try to correct one misconception given above about the intent of the patent system.
It's not just intended to protect inventors -- it's intended to give those inventions to the public. Before the first patent systems, most inventions were protected by simply keeping them a secret. Guilds went to extraordinary lengths (including outright murder in some cases) to keep their techniques secret. In some cases inventions have been lost completely -- anthropologists fairly routinely find artifacts made using techniques we don't know how to duplicate to this day.
So, patent systems were developed to provide something of a fair exchange: the government will provide some help in protecting your invention for a while. In return, you agree that after the patent expires, that invention enters the public domain so absolutely anybody can use it freely. Furthermore (and this is an important point) your patent is required to include enough teaching (aka. "Enablement") for a "person of ordinary skill in the art" to implement the patented invention. At least in US patent law there's also a "best mode" requirement, which means you have to tell about how the patent is intended to be used -- attempting to mislead a reader about the intended purpose of the patent can be enough to invalidate it.
While I think there's room for improvement in the patent system, I think there's quite a bit more there than most people realize, and it really is more beneficial for society than most people realize. Furthermore, I think quite a bit of what most of us take for granted in the way of technology being pervasive isn't really just how things are at all -- it's a fairly direct result of patent systems not-so-subtly encouraging inventors to publish their work, so it becomes available to society in general, instead of keeping it secret and (in some cases) allowing it to die with the inventor.
Photographers should probably be more aware of this than most others. Just for an obvious example, virtually every mainstream lens today (especially fixed focal length designs) is based on a design that was once patented, and became publicly documented and available for general use specifically because it was originally patented and the patent has now expired.
Summary: patent systems are intended to be a balance. They're designed to give the inventor a benefit in the short term, but in exchange give the rest of society a benefit in the longer term.