All right, Houston's out, so you can forget all of this. Now it's a White Sox-Tigers game that may need to be made up on Monday, if the AL Central race isn't decided by then. So that's one theoretical AL regular season game that could be played, in addition to possible White Sox-Twins and Mets-Brewers play-in games. (Actually, if the Phillies lose today and Sunday, things could get more complicated. But, for the moment, let's assume the Phillies win the NL East outright.) So what does all this mean for fantasy leagues?
Again, last year, Yahoo didn't count stats from the Rockies-Padres play-in game, so it's highly unlikely they'd reverse course this season. A regular-season make-up game might be a different story, though not according to one forum member at Fantasy Baseball Cafe, who yesterday posted that Yahoo answered his inquiry by stating that "the game ends on September 28th, the season will not be extended for rain outs." I haven't personally verified this.
ESPN and CBS Sportsline, on the other hand, did count the play-in game last season, at least for their standard roto leagues. (Not sure about head-to-head.) So right now I'd say it's likely that any games played on Monday or later will count for managers with leagues set up there.
Bottom line: If you're thinking about picking up players for Monday and beyond just to be safe -- and, really, why wouldn't you? -- guys in Tigers and White Sox uniforms are your best bet (ESPN currently has Garcia and Floyd as the starters), followed by Twins, Brewers and Mets.