u.s. forces in iraq currently operate under a UN mandate and "at the invitation" of the iraq government. the mandate expires at the end of the year. prime minister maliki is in the bush administration's pocket, so he will almost certainly invite u.s. forces to stay. that's what he did last time the mandate was about to expire. it was such a non-event it barely was mentioned in the u.s. media.
except that under the iraqi constitution all international agreements have to be ratified by the parliament. the parliament reflects the opinion of 90% of the iraqi public and wants u.s. forces out. so when maliki agreed to an extension last year, he didn't submit the extension agreement to the parliament. instead he made the legally dubious claim that the ratification clause didn't apply to the UN mandate.
as i mentioned at the time, last june the iraqi parliament passed a bill clarifying the matter and specifically requiring maliki to submit any extension of the UN mandate to the parliament for ratification. under the iraq constitution, the prime minister has 15 days after a bill passes parliament to veto it. if he doesn't veto it, it becomes law. in this case, 15 days passed and maliki never vetoed the bill. so that means the requirement that any extension of forces agreement be ratified by the iraqi parliament is now law.
but it looks like maliki is going to ignore iraqi law and approve the extension himself once again. and it looks like the UN is trying to give him cover to do so.