Interestingly, the Dyson design was based on an existing cyclone system widely used to separate out dust and particles in industrial settings. The innovation was using the process in a domestic vacuum cleaner.

So it's not too far removed from the "thing-that-already-exists but on the internet" patents which are a large part of the problem, or the "thing-that-already-exists but on a mobile" patent which is biting Notch's ass at the moment.

Not that I'm saying Dyson's patents are invalid, nor that his designs haven't improved the state of the art in several fields, but he didn't invent the cyclone technology in a... vacuum.