According to this post by Roger Dingledine, two tor directory servers were compromised recently. In that post Dingledine said:
In early January we discovered that two of the seven directory authorities were compromised (moria1 and gabelmoo), along with metrics.torproject.org, a new server we’d recently set up to serve metrics data and graphs. The three servers have since been reinstalled with service migrated to other servers.
Whilst the direrctory servers apparently also hosted the tor project’s svn and git source code repositories, Dingledine is confident that the source code has not been tampered with – and nor has there been any possible compromise of user anonymity. Neverthless, the project recommends that tor users and operators upgrade to the latest version. Good advice I’d say – I’ve just upgraded mine.