Dave Weigel breaks it all down nicely. Money quote:

As happens so often in the #Benghazi scandal, the outrage is not the new information but the fact that the new information was “covered up.” Had the Rhodes email been part of the 2013 delivery to the House investigators, we would have known, then, that the White House attaboyed the “demonstration” story one more time and urged that the administration’s spokesflacks “reinforce the President and Administration’s strength and steadiness.” (This is a major departure from most crises, when administrations try to broadcast fear and panic.**) How might the coverage have changed? We’ll never know. Why didn’t this email emerge then? Fair point, it really does look like the administration chose not to send every single email from the Night of the Talking Point, and that this one looked a bit worse than what was sent.

But it was largely redundant. The Rhodes email doesn’t change that the talking point that blamed the attacks on a confusing demonstration, as part of the Arab world’s reaction to the “Innocence of Muslims” videotape, came from the CIA.

More: Smoking Gun: Shock #Benghazi Email Reveals That Obama White House Agreed With CIA Talking Points.