This morning the Hadley group has confirmed that the emails that were published as a result of the hacking appears to be genuine, as based on this report.
There is speculation that this wasn't necessarily the work of a hacker, but an insider blowing the whistle, claiming that Hadley cancelled all existing passwords. That could simply be a precaution to institute stronger password protection, such as requiring longer passwords and requiring multiple numbers and case-sensitivity, and not necessarily the result of leaning towards an inside job.
If these emails are indeed genuine, they throw into question analysis and data collection techniques used at the center. The security breach was first uncovered by the folks at Real Climate, who passed on the information to the Hadley group.
Watts Up With That has some of the jucier tidbits, including emails purportedly claiming that they would hide declines in global temps by overlaying different data.
Data collection and analysis is at the heart of the global warming theory. If someone is fudging data and/or clearly trying to massage the data to fit a theory, it's grounds for serious repercussions seeing how nations all over the world are looking to spend and/or tax carbon emissions into the ground (literally and figuratively). It's literally a trillion dollar question, and if the data was indeed fudged, it throws into question the accuracy of the data.
University of East Anglia Climatic Research Unit is the name of the entity involved, not Hadley. I've corrected above.