It was back in April, in association with an attack on Linode [1]. See this HN comment by RoboTeddy from yesterday for a great summary of the group's story about these attacks [2].

However, Name.com has not disclosed much information. I don't know if they were aware of the attack until the group released their story yesterday. The systems could have still been compromised.

[1] https://blog.linode.com/2013/04/16/security-incident-update/

[2] https://news.ycombinator.com/item?id=5667391