This WaPo story suggests what we probably know to be true. Fitz has always been aiming at Cheney, and Libby has rather clumsily covering for him.
It's interesting really. For a long time I think it was CW that this all led back to Rove based on Rove's general approach to things ("fuck him like he's never been fucked before!") That drove a lot of speculation about the sitation. But, all along, The Snarl was up at the top of the pyramid.
I understand the concept of loyalty, but not the kind of hierarchical loyalty we see here in which loyalty involves underlings taking the fall for their bosses. True loyalty is a two way thing, but it looks like Cheney threw his pal under a bus.