Great little quote from Sky Yaeger (Bianchi VP and designer of lots of their bikes, including Pista and P-concept) in the current Riv Reader:

"I am baffled by urban hipsters riding fixed gear track bikes as fashion accessories and finding out they are not as practical or safe as they thought. I'm not talking about messengers or skilled riders, just to be clear. But most people should be riding a bike with brakes and a freewheel." -while discussing the San Jose.