If it really was a Russian Hacker, kinda doubt that cover story, their primary interest would be cash. So perhaps the BBC was being blackmailed over something - or else this information dump would be leaked. Perhaps the BBC failed to cover the minimum bid. Russian hackers have acquired expensive tastes of late.
There really is no evidence that the hacker was a Russian except for the fact that the data dump was via a free Russian File Sharing site. That's not enough to convince me. The evidence that it was leaked or "discovered" is much stronger based on the makeup of the file-set (very FOIA-like) and the file name itself: FOI2009.zip. This is not a random set of files. The Happy Birthday and I'm on vacation stuff etc. is totally absent. These files were carefully selected, something an insider could do and only a very knowledgeable hacker could duplicate.
So the best current theory, IMHO, is that these files were prepared by CRU as an FOI response and either leaked by a whistleblower or (foolishly) left in a publicly accessible location on the CRU server and were just stumbled upon by someone with an interest in releasing the data.
In any case, it is quite a story and I think it has legs. Rush spent nearly an hour on it Monday, Beck gave it 10 minutes or so and it was on Bret's show on Fox as well.