I've been to San Fermin four times and would really like to be there right now. On one of the runs in 1999, I saw a woman in high heels and a party dress run (walk actually, up Estafeta). It was obvious she was trying to make a point (though I'm not sure what it was). Last year (2001) the Police seemed a little more aggressive about keeping really intoxicated people off the course. They were especially strict about cameras being used on the course. If they saw you taking a picture in the encierro, they grabbed you and your camera and tossed you out.
On a lighter note, I wholeheartedly suggest that you run if you think you would like to. It's not a bad idea to watch a run or two before you try it. I generally try to move away from anyone I hear speaking English before the rocket fires and the Bulls are let loose. Not that I'm some sort of expert, but it seems that some of us Americans just don't take it seriously enough:-(.
Keep in mind that you are more likely to be trampled by your fellow San Fermines than by the Bulls... and...if you fall on the course...STAY DOWN AND DO NOT GET UP UNTIL SOMEONE TAPS YOU to let you know it's safe to get up.
Viva San Fermin!
Gora San Fermin!