Re: Dr. Andy's post about compulsory vaccination, I have a couple anecdotes.
When I spent a summer in DC I had the opportunity to attend a congressional hearing on Hormone Replacement Therapy. At one point the committee chairman went on a diatribe about vaccines and autism, and how his grandson is autistic and clearly it's the vaccine's fault. Then he said asked the chairwoman of the heart, lung, and blood institute why the NIH wasn't doing anything about this (gee -- I don't know, because it's the FDA's jurisdiction??). Keep in mind this has nothing to do with Hormone Replacement Therapy, which is for menopausal women.
Next in Kate's special anecdote file is the girl who got measles in one of my classes at Santa Cruz. Now, being Santa Cruz and all, this wasn't too terribly surprising (not because there's lots of measles going around, but because there's a lot of ultra-natural people). But a 20 year-old got measles! It's ridiculous.
The main issue I have with "conscientious objections" to immunization is the person who it really affects isn't choosing at all. They could get something terrible like, say, measles (or heaven forbid, Hepatitis B), down the road because of their parent's scientifically unfounded beliefs.
Fortunately we're fine as long as the vast majority are vaccinated. Who knows where my classmate got measles from, but she didn't spread it to anyone else.