Pay attention to the movement in the back by the glowing sphere to help get an idea of how many people are moving. I think the overall ticket sales were \~80,000. I'm sure they weren't all there, but a lot of them were.
Note: if you do not like crowds, these type of music festivals are probably not for you. At least not the headliners for each night. During the early parts of the day, it's not bad at all. For the last shows of each day, everyone gathers around one of two stages and then all leave at the same time when the set is over. I find the resulting mass of people in various stats of inebriation fun to watch.
This was shot on my recently acquired F200 point and shoot. Once again, I'm blown away with the quality little consumer cameras can capture these days.