Didn't think much of it as I rolled over somethign that went POP! -- until I was parked at the corner of Hudson and 10th waiting for a light when my rear tire blew out. Just standing there. Sounded like a gun going off.
Luckily there was a bike shop two blocks away, friendly folk. Not only did the tube blow, but whatever it was that I rolled over at the beginning of the ride had shot a big hole in the tire itself. Replaced both for $40. Whole new ride.