Obama campaigned for Chicago to be selected for the 2016 Olympic Games. The decision will be announced in a few hours, but do not think there is much suspense to this. I do not think Obama would risk the embarrassment of using his clout to get the games and failing. One of his biggest 'selling points' as a candidate was how much more the rest of the world will like us. That has not really panned out, especially for our allies, but I do not think he could risk this obvious a rejection. With that in mind, I think the decision was already either made or arranged before he left.
More when the announcement is made.
Video embedded below.
Update (10/2/2009): So much for that idea (Berman Post: Chicago Eliminated in The First Round of Voting to Host 2016 Olympic Games)