In Omaha, red-light cameras are required to take two pictures of you(on the same film, as I read it). One with you before you enter the intersection, one with you in the intersection. Both pics must show that the light is red. These cameras have been placed at high-traffic intersections. Surrounding traffic/lighting/etc doesn't change that much between before you enter and when you're in the intersection. Thus the city and the police both have proof that you entered when the light was red.

Trouble with this is that not every Linux project becomes a newsmaker. What of the ones that have quietly & slowly shifted to or from Linux? What of the ones that have shifted to or from Linux, but wanted the change to remain quiet for security reasons? What of the ones who announce such a change, but never makes it past the newsmaking stage(some for security reasons, some for political reasons, or some for some other reason?)

Those will all throw off the map, and when we're dealing with market share/penetration in the range that we are with Linux, even a small change will affect it significantly?