The Washington Independent has the scoop. Basically, Bush and His Evil Minions^™completely caved to Iraqi demands.

You’ll recall that they pushed back the date to 2011, for, as Nouri al-Maliki admitted, for US domestic political reasons, and that is what it says in sub-article one of article 25 of the agreement:

The U.S. forces shall withdraw from Iraqi territories no later than December 31 2011.

But wait, there’s more, there is also sub-article 6:

U.S. forces may withdraw from Iraq before the dates indicated in this article if either of the two sides should so request. The U.S. government recognizes the Iraqi government’s sovereign right to request a withdrawal of U.S. forces at anytime.

So we leave when we’re told to leave by al Maliki, and indirectly by his sponsors in the government of the Islamic Republic of Iran.