Actually the park service refuses to issue estimates of the crowds at rallies (with the exception of the presidential inauguration) -- they were threatened with legal action after estimating that the million man march had less than a million people. If you have official numbers from a U.S. Parks service official source I would love to see them.

I realize that actually being there is an unscientific measure of the number of people in attendance (for one I was at the Beck rally from noon until about 4pm and the Stewart rally from about 11am until 2) but the density of the Stewart rally was certainly higher, enough for me to eventually leave. Beck supporters allowed for a lot more personal space which made it more comfortable, but also means a weaker density of people.

There are some services that use aerial photos and scientific means for counting people - I don't think we'll know for sure who had more until those numbers come out. In the end, it doesn't really mater, both groups were able to get their word out on the mall and exercised their rights as Americans to assemble peacefully. That is really what counts.

I actually went to both Beck's rally and to the Stewart/Colbert Rally as I live near the mall. Stewart/Colbert felt a little more crowded across the entirety of the mall than the Beck rally but it was probably about even in terms of turnout overall. On average, Beck supporters are 25% bigger than Stewart supporters (no judgment on either overweight suburbans or over-skinny hipsters). As for jumping the shark, I don't know, I couldn't hear anything and left after walking up and down the mall. Both rallies attracted their fair-share of weirdos but I'd wager that that is just the nature of rallies. Any of us that judge Beck or Stewart based on the 2% of kooks at their rallies should probably recognize that the judgment isn't too fair. Let them each have their day on the mall; it is, after all, a free country. Also, among the signs I did see many that said that were pro-conservative, republican in nature, which was good.