Confirmed: Of course CBS knew this bit of information when Rathergate aired back in 2004 leading up to the election but chose not to inform its viewers. You see a story about the current president trying to get out of his remaining service commitment doesn't quite jive with someone volunteering for Vietnam missions. See Wizbang for more. Here's the confirmation part of Goldberg's piece at his website;
Who says? The outside panel CBS brought into to get to the bottom of
the so-called "Rathergate" mess says. I recently re-examined the
panel's report after a source, Deep Throat style, told me to "Go to
page 130." When I did, here's the startling piece of information I
Mapes had information prior to the airing of the September 8 
Segment that President Bush, while in the TexANG [Texas Air National
Guard] did volunteer for service in Vietnam but was turned down in
favor of more experienced pilots. For example, a flight instructor who
served in the TexANG with Lieutenant Bush advised Mapes in 1999 that
Lieutenant Bush "did want to go to Vietnam but others went first."
Similarly, several others advised Mapes in 1999, and again in 2004
before September 8, that Lieutenant Bush had volunteered to go to
Vietnam but did not have enough flight hours to qualify.