This almost happened back in 1948, but the Red Sox lost a one-game tie-breaker with the Cleveland Indians—who went on to beat the Braves in the World Series. Think of what could have been! A short commute Fall Classic—between Fenway Park and Braves Field (the current site of B.U.'s Nickerson Field). Alas, since the Braves are now in Dixie, it's more like a 1,000 mile drive—but still, it would be the first World Series match-up between two original Boston franchises.
Of course, Inter-League Play (which started in 1997) has severely diluted the potential sweetness of this possibility—since they matched up four times just this season (the Red Sox wining three of four, by the way). Still, forcing the Dodgers and Astros to play golf the rest of October would almost be sweet enough in and of itself.