Milwaukee lost the first game of their double header against Philadelphia this afternoon, so the Cubs' magic number is now 9.
Update, 21:00 CDT: The Brewers just lost 6-1. The Cubs' magic number falls to 8, with 16 games yet to play.
Later update, 21:15 CDT: The Cubs are right now schooling the Astros 5-0 in the top of the 9th at Miller Park. So despite the rain, today is turning out pretty well for the Cubs.
Final update, 21:30 CDT: Thanks to a 7-inning no hitter by Carlos Zambrano—the first Cubs no-hitter since 1972—the Cubs beat Houston 5-0, lowering their magic number to 7.