Recall that once CryptoLocker infects a computer, it encrypts all documents it can find, making them inaccessible until you pay the perpetrators $300 for a key to unlock them. Thousands of users have been hit, with some paying the ransom, while many others lost their data forever.
The researchers have set up a free web site (2016Jan09: the site has been decommissioned) that allows anyone hit by CryptoLocker to decrypt their files. You must upload one encrypted file, after which you are sent the required key. After decrypting your files, you can then use a CryptoLocker removal tool to get rid of the infection.