The AP's report as of Saturday evening shows CBS beginning to back down:
"WASHINGTON — CBS News acknowledged memos it received about President Bush's service in the Air National Guard (search) were difficult to definitively authenticate, but said they came from 'solid sources."
Translation: "Difficult to authenticate" = "Oops, we ran with the story without fully checking it. Who thought anyone would notice?"
Of course, Bush probably did use pull to get into the Guard, and probably did slack off at the end (when the war was winding down). We knew this. What this clarifies is what biased hacks the MSM are.