CBS has had the original memos all along. They produced the reproductions themselves to try to taint the documents and give the WH an opening to deny all of it -- both the memos and the underlying events (best case, Bush says he was never directly ordered to take a physical). Then Dan Rather whips out the originals and proves Bush is lying.

But this is so wacky that even I don't believe it. :p

I'm wondering if at some point somebody scribbled the memos from the copies onto notes, or if the original handwritten memos are somehow around.

These memos have too many personal touches to seem to be wholly made up from a long memory.  I'd put more credence that somebody scribbled notes, and then reproduced the memos, or Killian kept his handwritten memos, or copies, and the CBS memos were reproduced from these.

She hates Bush, typed the originals that have since been destroyed, and could have most easily recreated them of anyone. That was a long time ago, who would have an advantage in that regard? The person who created the memo, or someone who had read it?

Perhaps she wanted to remain in the shadows but now that the memos may really tank, she is stepping forward to change the subject.

My vote: Killian himself. As his secretary has said, his original CYA file had probably been tossed after he retired. When he retired, Shrub was even more of a nobody than he is now; I'm sure Killian didn't give his letter a second thought at the time. Later, however, he may well have wanted that letter back, once the Georges Bush became even more prominent. And if there's one person around who would have known what was in those memos, it was Killian himself.