Here's detail from a InformationWeek story, "Hackers Blamed For Data Breach That Compromised 300,000:"
A hacker broke into the computer network at the Illinois Department of Financial and Professional Regulation this past January and accessed a server that held information on about 1,200,000 people who have licenses or applied for licenses with the department. Susan Hofer, spokeswoman for the department, said in an interview that about a quarter of the stored information was compromised.
A quarter of the information? Really? I'd love to understand their logs, which seem to be well designed. Compare and contrast to all the organizations that say "we're not really sure what happened."
Kudos to the Illinois Department of Financial and Professional Regulation for having good logs.