The meeting was called by President Bush to discuss Iraq. There isn't going to be anything serious discussed with Mcnamarra there. But the president is trying to build consensus for Iraq and by extension for the coming Iranian showdown.
This may be a "14 Days in October: The Cuban Missile Crisis" kind of showdown. They may think they have us hotied, but they know in their hearts that if George W. Bush says he's going to do something, he will do it. IOW, they might back down. For now.