From a co-worker: According to a United pilot, an in-place contract between Continental and either Northwest or Delta is no longer valid due to the announced Delta / Northwest merger. This opens the door for a merger between United and Continental.
Mergers reduce competition and choices for the customer. In most cases, this will result in higher prices. On the bright side, depending on your location, it could mean more choices to fly and more flexibility of your (constantly de-valued) frequent flyer points.
Let the courting process begin.