Someone in the Department of Justice should be fired, but it's not necessarily Attorney General Alberto Gonzales. It's whoever from the public relations arm of the DOJ prepped him and didn't forbid him to use the phrase "mistakes were made." The classic passive may have worked when it came out of Reagan's mouth, but it has long since passed its life and is used mostly for satirical or antagonistic purposes now.
I find this choice of wording inexplicable, given that there are almost equally weaselly ways to avoid describing oneself as the person actually responsible while still sounding much more definite and active. Compare Gonzales's I acknowledge that mistakes were made here. I accept that responsibility with Members of the Justice Department made mistakes, and as the head of the DOJ I accept that responsibility. The latter would make Gonzales sound like a strong leader ready to clean house -- even if it's only to the extent of admitting that there should have been more disclosure to Congress without admitting any underlying error in the firings themselves. The former makes him sound like a guy asleep at the switch, belatedly waking up after the crash.
As for the substance of the scandal, I'd advise Democrats (i.e. Conyers and Schumer) not to invest too much in "getting" Karl Rove on this one any more than he was "gotten" in the Plame affair; with one aide who resigned yesterday, and Harriet Miers as an easy scapegoat who resigned back in January, there are enough low-level players to blame that Rove can escape responsibility. And he may well have had very little to do with the idea to fire all 93 chief prosecutors, a notion from which the Bushies backed down despite Clinton's having done it shortly after taking office. One of the benefits of Rove's working at the highest level without any defined place is that such day-to-day business rarely can be attributed to him.
UPDATE: The NYTimes calls it a "familiar fallback."