This is pure speculation.
But. . . I can't help suspect a link between (1) firing/replacement of US attorneys and (2) Cheney.
OK. A Rove connection is still a strong possibility given his long, concerted effort in depriving Democrats of the right to vote.
On the other hand, there are some markers along the trail that could lead to Cheney.
Gonzales
Albert Gonzales is shown by the WaPo articles on Cheney this week not to be his own man. We already knew that. What we didn't know was how much a cipher for Cheney's henchman, Addington and Yoo, he really was/is. He doesn't write his own orders, his own letters, his own opinions.
Gonzales' denials of knowing about what goes on in his own Department of Justice may not have been a subterfuge at all. If he's ceded effective control to Cheney's office, then he probably never has known what's going on.
Harriet Miers
As Gonzales, Miers was apparently willing to do Cheney's bidding happily. Any signs pointing to her role in removing USAs may need to be re-viewed as pointing toward Cheney.
Cheney
Bush may be a non-player after all. The WaPo article brings a great deal into focus about the dynamics of the White House and the administration. At the very least, the USA firings/replacements couldn't have happened without Cheney's acquiescence. But it may be that Cheney has a direct role in the USA scandal. He seems to in everything else of substance.
Of course it could be that the USA scandal is still Rove's primarily. But I can smell a Cheney connnection--even all the way from Texas.