As Josh noted below, Rove's involvement with the U.S. Attorney purge is hardly a surprise. Here's what the Washington Post reported in early February:

One administration official, who spoke on the condition of anonymity in discussing personnel issues, said the spate of firings was the result of "pressure from people who make personnel decisions outside of Justice who wanted to make some things happen in these places."

Hmmm. People outside of DOJ who make DOJ personnel decisions? That's a one-item list: the White House. Yet, as late as Friday, even the esteemed Dan Froomkin said, "Just how closely was the White House was involved in these firings remains a mystery."

The precise details are yet to be determined, but the White House involvement in this purge hasn't been a mystery for more than a month.