The one and only pro roadie I know just posted this article about some new trends in the pro peloton for 2013 on his FB and I just had to pick up this passage:
"Urban messengers and their fakenger cousins have long known about narrow bars letting you squeeze in between traffic, even cutting their bars shorter than the width of their hips. There’s a benefit in racing too as riders can get into smaller gaps with narrower bars, something that matters for sprint trains. However high speed stability and control can be sacrificed."