In a December 30, 2007 memo written on the eve of the Iowa caucuses, Mark Penn writes to his fellow Clinton staffers that after the caucuses, if Obama "is riding a high we will have to take him down."
He runs through a series of potential attacks against Obama -- he has taken a bunch of liberal positions that make him unelectable, has been inconsistent on Iraq, has flip-flopped on issues, and voted present a number of times in the Illinois legislature instead of taking a position.
Then, playing out a number of scenarios, Penn writes that if they come out of Iowa and it's a two-way race with Obama, "on Friday we do a media interviews (sic) and basically say that he is unvetted, discuss his ever-changing positions. Release the tapes. Create immediate pressure that deprives him of oxygen.'
"Release the tapes"????
UPDATE: Ben Smith at the Politico and Sam Stein at Huffington Post say that a Clintonista reports the tapes were video of Obama taking ultra-liberal positions that don't square with his current stated views, nothing more nefarious than that. For what it's worth.