If one can see past the "postwar game" commentary in this passage [below], there is an interesting term "north and south nod" which is captured in the headline "Nodding is not planning".

"General Garner said the administration's mistakes had made it easier for the insurgency to take hold.
"John Abizaid was the only one who really had his head in the postwar game," General Garner said, referring to the general who served as General Franks's deputy and eventually his successor. "The Bush administration did not. Condi Rice did not. Doug Feith didn't. You could go brief them, but you never saw any initiative come of them. You just kind of got a north and south nod. And so it ends with so many tragic things."

http://mathewgross.com/blog/archives/000846.html

One can nod in assent, or one can nod off.

One can also nod when that is the safest thing to do.

But the "north and south nod" is really a shrug. It's an "I-agree-with-you" nod, but "don't-expect-me-to-stick-my-neck-out" up and down motion.

You know for certain you are getting a "north and south nod" if the nodder's eyes are glazed over.