Might have been already posted here, but Tim Blair has this:

Veteran Nashville broadcaster, Teddy Bart on his daily radio show, ìTeddy Bartís Roundtableî may have given us a clue about who knew about the documents nearly a month ago. It appears that Bob Tuke, who was a guest on the show on August 11th knew that something was about to happen with regard to President Bushís alleged failure to show up for a physical examination.

Teddy referenced the episode yesterday (September 9th) when 42:13 seconds into the show he said, ìListeners to the Roundtable will note that something was going to come because Bob Tuke, who is a Nashville attorney and significant in the Kerry campaign in Tennessee, told us about three weeks ago that um there was going to be some document, or implied that there will be a document about Bushís missing time in the Alabama National Guard, in the National Guard, and that somebody was going to come forward with a document. So it did happen, and uh 60 Minutes had it.î