It's important to keep a close watch on your credit and look out for any signs of identity theft. It seems 3.6 million social security numbers and a large number of credit/debit card numbers were taken. One article mentioned that the numbers were from taxpayers' records going back to 1998.

http://www.wltx.com/news/article/206768/2/Hacker-Takes-Millions-of-SC-Citizens-Personal-Info