If you read the story it's clear that Fitzgerald knows Miller talked to Libby sometime soon after Wilson's editorial appeared and before Novak's column. (It was probably on the day Wilson's editorial appeared, from other accounts.)
The article mentions two sources, one from Libby's and one from Miller's camp. The latter seems to be the source for the claim that Plame never came up in their talk.
So it looks like this is what it boils down to. Libby is saying he was told about Plame by Miller. And Miller is saying it isn't true (through her mouthpieces) but won't testify about that, so as not to have to reveal where she heard about Plame in the first place.
Not quite what the WaPost and NYT had in mind when they kicked over this rock. hehe
I doubt the extent of Miller's involvement is what she might have said to Libby 2 days before Novak's article.
I suspect there's something earlier.