How did Moore know?

Apparently, the attack upon the president over those National Guard memos was quite well known in liberal circles. Take a look at this blog posting over at Michael Moore's site, on Sept. 7--one day before the CBS broadcast was made:

Later today (Wed.), the Boston Globe, the A.P. and Dan Rather all present new and damning information about how George W. Bush got moved to the front of the line to get in the Texas Air National Guard, and how he then went AWOL. I am putting every ounce of trust I have in my fellow Americans that a majority of them get this, get the injustice of it all, and get the sad, sick twisted irony of how it relates very, very much to our precious Election 2004.

How did you know, Mike? Sounds like everybody in those circles had a heads up.