Recently some journalists have been getting very excited about BBC journalist Paul Hudson's supposed complicity in all this. When the story first broke, Hudson quickly reported "I was forwarded the chain of e-mails [just the small subset relating to an article he wrote] on the 12th October" - a month before the widespread release. Many people initially attributed this to a careless slip really meaning 12 November, but Hudson confirmed explicitly that he meant October, saying "I was copied in to them at the time".
But....he wasn't. The email addresses of all participants in that sequence of messages are clearly identifiable, and none of them are he.
The obvious conclusion, which may explain why he has been a bit coy about all of this, is that one of the participants forwarded these email to him rather than including him in the conversation. That is, they secretly divulged private email conversations to a journalist. Not that there is anything particularly noteworthy or scandalous in the emails, but if I was talking about someone behind their back, I'd be a little surprised to find a colleague was forwarding my comments directly to them. It seems that at least Hudson is adhering to his journalistic ethics by not revealing his mole. Not so long ago, a prominent climate scientist was sacked for unauthorised contact with the media, so perhaps it's just as well!
[OK, it's theoretically possible that he was openly forwarded the emails with the prior agreement of all participants, but that those messages have not found their way into the released set, but it seems a bit improbable.]