From Nature's recent interview will Phil Jones
...the hack of the server was a sophisticated attack. Although the police and the university say only that the investigation is continuing, Nature understands that evidence has emerged effectively ruling out a leak from inside the CRU, as some have claimed. And other climate-research organizations are believed to have told police that their systems survived hack attempts at the same time.
Not that this is a particularly surprising conclusion; Frank Bi has been investigating the CRU hack since the story broke, almost exactly a year ago. The whole notion that it was an inside job by some dissident CRu employee never had much credibility among those not wearing tin-foil hats.