Yglesias says the NYT's speculations on the composition of the Obama administration are ill-founded: "the Fed Chairman is more important than the Treausury Secretary," so there's no reason Paul Volcker, Robert Rubin, or Larry Summers would want to run Treasury.
But isn't the Treasury Secretary more important now that: (a) s/he's in charge of a big chunk of the banking industry; and (b) the economy's in too deep a hole to be rescued by monetary policy? The next administration's response to the recession is going to have to involve substantial fiscal stimulus (unless the next administration is staffed by lunatics), and you'd imagine the Treasury Secretary would be heavily involved in that.
In a way the Treasury Secretary is like one of those hammers kept behind a thin pane of glass -- most of the time it's just sitting there, but it's really important in an emergency.
(Perhaps RoBros legal advisor and former Treasury intern Ty Alper could weigh in.)