Last year, I reported on the 2008 Naked Bike Ride in St. Louis, the first ever in my home town. The official purposes are twofold: to protest dependency on oil and to celebrate our bodies. It’s also a blast riding through town without having to worry about motor vehicles and without having to wonder what one’s fellow travelers look like naked (or almost naked). 
This year’s St. Louis Naked Bike Ride occurred tonight, with perfect temperatures for not wearing much of anything or not wearing anything at all. I’d make a wild guess and say that there were about 1,000 bike riders tonight, 70% of them male. I’d also guess that about 20 of them were riding completely naked. I saw people from 16 to 70 years of age. Lots of camaraderie–the riders were warning each other of potholes and other road hazards. I only saw a few spills–luckily, those falls involved people with some clothing to protect them. 
The genius of this event’s marketing is that every local media outlet was out there reporting on the event. Imagine having a clothed bike ride to protest oil dependency. You would probably only have the attention of a few eccentric bloggers like me.
Speaking of which, I was there tonight (wearing boxers), riding a course that was modified (shortened to about 7 miles) at the last minute, apparently to avoid the outflow of a huge crowd from a Cardinal Baseball game downtown. We wouldn’t want those people to be embarrassed were we to ride by and see them dropping exorbitant amounts to amuse themselves–$50 for tickets and $7 for hot dogs. Not while we–the naked and almost naked riders–were out there protesting oil and admiring and celebrating each others’ nakedness, all for free.
I would like to point out that the aim of this bicycle ride to celebrate our bodies is not a trivial issue. Refusing to celebrate the human body is closely related to our refusal to consider that humans are animals. These two dyfunctions are the cause of constant needless and useless human suffering. See this earlier post on terror management theory and this post on the dysfunction that stems from our failure to accept that humans are animals.
Had I known about this in advance, I probably woulda joined in. I riding out of the park on my tandem at the time the ride was getting started. But I was not prepared for an after dark ride, and had just completed a couple of hours of folk dancing in front of the inflatable screen where they were about to show a movie.
For those interested in knowing more about the reason for this ride, consider visiting this Wiki page.
I found the FAQs from the national NBR organization especially well considered.
Oops, I read 2009 and accidentally commented on the 2008 post. Either way, this was a cool event. My husband rode- you can read about it and see pics on my blog at http://www.havesporkwilltravel.blogspot.com
I looked over the wiki you provided to see if my main qualm- injury- was covered. The wiki only suggests that a rider wears a helmet and tries not to fall. It seems like a nasty scrape or chafe could occur, though.
A similar event should be staged in areas where all people can go topless legally. Call it "critical titical mass". Perhaps that's too absurd.
I've fallen on my bike a few times and clothing can be of dubious protection. It doesn't take much sliding on the road to tear big holes in the clothes which means you get road rash. Honestly, unless you're wearing some sort of seriously abrasion resistant stuff you'll get a bit of road rash.
That said, you're also pretty darned unlikely to injure yourself on a bike. Riding your bike is one of the safest things you can do. Fewer injuries per hour of operation than driving or walking down stairs, and there aren't too many of us that live in ranch homes here in the city. Chafing on such a short ride isn't an issue especially if you have a nice saddle.
The bike ride was a blast. Second year for me, I was the guy in litigation yellow briefs riding the Xtracycle with two kid seats on the back (kind of like a pedal powered woody station wagon) with "One Less Minivan" painted on my back. The after party at Atomic Cowboy was both surreal and exhilarating. The worst part is that it's another year until the next naked ride.