Ben Smith:

Senator Clinton intends to remain in office through confirmation," emails spokesman Philippe Reines.

UPDATE: Says New York Governor David Paterson in a statement: "In order to appoint the best possible candidate to replace Senator Clinton, I am consulting with a wide variety of individuals from all across New York State. I expect to announce Senator Clinton's replacement when the position becomes officially vacant."

This isn't a surprise; were it the other way around (Hillary Clinton announcing her resignation from the Senate before her confirmation as Secretary of State), it would have been huge news. But as is, this was to have been expected.

Only nine times in the history of this country has the Senate voted down a cabinet nomination. Not one of those nine failed nominees was a sitting United States Senator. Why? As John Dean explained in "The Rehnquist Choice: The Untold Story of the Nixon Appointment That Redefined the Supreme Court" when discussing Richard Nixon's potential nomination of Robert Byrd to the Supreme Court, the Senate is extremely unlikely to reject a nomination from its membership because a rejected nominee would have the power as Senator to seek retribution against members voting against him or her, through filibusters, through holds, and the like. In the not too distant past, the Senate has rejected a former member, John Tower, but again, former members, unlike sitting members, don't have the capacity to hit back against Senators voting against his or her nomination.

This isn't to say that Clinton would otherwise have difficulty getting through the nomination process, because I don't think she will. That said, when one has leverage in politics, there is no reason to give it away for free, so it makes eminent sense for Clinton to hold on to her Senate seat until she is confirmed.