One of my friends had her bike stolen this week. It was locked up with a cable lock at a parking garage bicycle rack. I hate bike racks in parking garages, and this is one of the reasons, that they seem particularly prone to crime. Here's a rack I encountered recently. And this photo was taken from only halfway to the entrance of the garage - from outside you could hardly see it at all.
Protect yourself. Always use a U-lock. If you need a cable lock to secure your quick-release parts or because a U-lock won't fit around the thing you're locking to, use it with a U-lock. I have a cable with no lock, just loops at the ends that I can secure with the U-lock that goes through my frame.
You can also double or triple up on your cable locks - it will only slow a thief down by a little bit, but will make your bike less attractive than the single-locked bicycle next to yours. The really thick chain locks, like they use in Amsterdam, are effective too. And parking in a visible location can discourage, but not completely prevent, someone from cutting your lock.
And if you see an older black Specialized HardRock, size small, with pink logos and a huge front basket, let me know!