After checking various Apple-related sites, it definitely seems that the claims of widespread hacking of the iTunes store are groundless, another case of Chicken-Little style reporting in the blogosphere.
I have been using the iTunes store for 7 years now, and have never had a bogus charge on the credit card I use with them. Maybe this has something to do with the fact that I have a 30-character randomly generated password. I changed my password yesterday anyway (no reason not to) - these “scares” are at least useful in that they remind you to change your password once in a while.