I do plan to have some thoughts on this "team of rivals" Cabinet concept, if I find time. The shorter version is that while it may be a good idea for a disciplined leader like Barack Obama to fill his Cabinet with strong personalities in this especially gutless, herd-minded age, the idea that this follows Abraham Lincoln's example is considerably off-base, the adorable Doris Kearns Goodwin notwithstanding. Though the media and popular historians love to see genius strategies in every move that popular past presidents made, at the time of his election, Lincoln really was a minor figure laboring under serious political constraints — winning a four-way election where you were not even on the ballot in many parts of the country will have that effect — and he desperately needed all major northern factions on board with his presidency, including unionist Democrats and various state party bosses. In other words, the original "team of rivals" was a bug, not a feature, and the avoidance of "groupthink" was very far from being one of Lincoln's most serious problems. Obama is in a vastly different and far stronger position.
Also, a memo to Hillary Clinton: Lincoln also chose his chief party rival, William Seward, as a Secretary of State, but that precedent may not portend great things for your historical stature. Once I started training to be a historian, I learned that Seward was one of the true giants of 19th-century American politics. Seward expected to be running Lincoln's administration, and understandably (though inaccurately) so, as he was a co-founder and longtime standard-bearer of the Whig and Republican parties. But what happened to Seward's public image after eight years as Secretary of State? He ended up a trivia question. The only thing I remember learning about William Seward as a school kid was "Seward's Folly," the purchase of Sarah Palin's moose-hunting grounds. Seward was so eclipsed by Lincoln that the schoolbooks even left out the fact that John Wilkes Booth's assassination conspiracy tried to get Seward, too, but only succeeded in stabbing him repeatedly in the face.
[Also published at Publick Occurrences.]