James Fallows of the Atlantic is immersed in research for his next book and has invited guests onto his blog for a few weeks. One of the guests is Lizzy Bennett, a marketing director for Timbuk2, the messenger bag folks in San Francisco. She commutes to work by bike and has posted several times on her commutes over the last week, here, here, and here. She talks about her first ride and gives some tips to people thinking about it. The last link includes a helmet-cam video of her commute to work on the San Francisco streets. Keep in mind this is not on an enthusiast site, but Atlantic Magazine's.
Most recently she polled "the Timbuk2 community", probably meaning colleagues, contacts, and friends, about why they commuted by bike and made a word cloud. Shown below, and in the post on the Atlantic site here.