It certainly exists, and depends a lot on where you ride and how you secure your bike. Between my wife and I, we always have at least one bike locked outside in the downtown core of a moderately sized city (about a million). My grand total theft experience...I had a $10 mini pump removed one night. I know from the tracks in the snow that people do frequently walk over to check out my bike, but are apparently deterred by nothing more than a low-end U-lock. Indeed the only theft that I've known amongst friends was two fairly new and mid-range bikes ('07 Jamis Auroras), which were secured only by easily clipped cables (one was also wheel locked using a U). The thieves made enough noise to wake a neighbour, and the bikes were recovered on the other side of their parking lot, where the thieves had apparently abandoned them while they went to fetch a vehicle.
Anecdotal, of course, and the situation in a more bike oriented city (where there are more professional thieves who aren't so easily deterred) would be different. But at least here, it seems that a few very basic steps to secure your bike are enough to keep it safe.