Matthew Yglesias links to this item explaining that President-elect Barack Obama has ordered all politically appointed ambassadors to vacate their posts by January 20th. Matt says:

I had always just thought of this is a kind of casual, widely accepted corruption. But recently I did learn the official story as to why this is good practice, namely that an important political supporter or a friend of the president is likely to have a much easier time of getting access to the Oval Office than any mere foreign service officer would. Thus, it's arguably better for the host country to have a political appointee than a career FSO. Therefore, this practice helps build good-will and so forth.

This may be true, but it should be pointed out that many ambassadors to posts that require actual trouble-shooting are often career foreign service officers. The United States ambassador to Chad Louis J. Nigro, for example, joined the foreign service in 1980. Is it really more desirable that the Ambassador to say, Holland, have easier access to the Oval Office than say, Mr. Nigiro? I'm doubtful.