Epsilon manages email-based marketing services for a number of large companies, so it had name and email address information for customers of the client companies. This information was obtained by attackers. While some have said the nature of the information means the breach is not significant, my immediate response to my peeps on Facebook was:
Whoever has this information from Epsilon could simply use it for targeted spam. More troubling, the attacker could spend some time working over the data with tools like MapReduce and mine profiles for customers to enable very targeted phishing email attacks.
In what I would say is a good, proactive response, Epsilon and its clients have been very quick to contact affected customers about the issue and let people know about the dangers of the information leak. If there are any positive results from this breach, it should improve the security awareness of the average consumer and make companies think even more seriously about data loss prevention & database access monitoring.