Shelby off the Hook
The speculation was that Shelby, then Intelligence Committee Chair, had leaked information to cast the CIA (often criticized by Shelby) in a negative light.
The alleged leak(reported by CNN) contained information that the CIA had a document on Sept 10, 2001 indicating that attacks were to occur the next day. Shelby has never directly denied being the source for the report, but has stuck to never "knowingly" disclosing classified information.
The details of this are murky and don't look likely to be cleared up anytime soon. Though Shelby cruised through re-election with this over his head, I'm sure he is breathing a little easier now that this matter is closed.