How common is data theft?

According to this securityfix post it's a daily occurance. The email that he cites was from a woman who was informed by a company that a data backup had been "lost track of". There is a web site that chronicles such data security breaches. privacyrights.org. It's certainly worth a look.

Unfortunately on the biggest/biggest names involved get much news coverage. The real problem is that it's too easy for a "dishonest insider" to get away with tens of thousands of names and credit card numbers. It's not limited to just those that do business online or purchase online. It is a basic data security problem that anyone with a credit card number (or even social security number) has to be aware of.

Check your credit report(s) and check statements very carefully.