In fact, where we're at now is:
There are three games left for Los Angeles and Colorado. San Francisco is out of it. Both the Dodgers and the Rockies are going on to the postseason, the question is which one will do so with the NL West pennant, and which will do so as the wild card. All the Dodgers need to do in order to take the pennant is to win one of the three games.
Also important is the overal standing in the NL. The four playoff teams have records as follows:
St. Louis has a three-game series left at home against Milwaukee. Philadelphia has one more game at home against Houston tonight (it's 2-0 Astros in the botom of the 5th as I'm writing this) and then a three-game series at home against Florida. Sweeps in both cases are not out of the question. So homefield advantage is very much in play and it's available to, in theory, any of these four teams.
I suppose it's fun when it comes down to the wire like this. And the Dodgers control their own fate; if they sweep the Rockies, no one can touch them. But if they keep on playing the way they have been, they'll be facing down the Phillies away from the home crowd. For what feels like the past three weeks, the Dodgers have been watching their magic number slowly decrease but they just haven't been able to close the deal. So for all the math and complicated possible scenarios, it's really very simple. There is no more breathing room. Nothing less than a three-game sweep of the Colorado Rockies will do.
Also note a rather interesting race to the AL Central Pennant; Minnesota and Detroit split their series and that's still interesting -- the allegedly sign-stealing Minnesota Twins are down by two games but they get to finish out their season with a three-game sweep against the AAA Kansas City Royals; the Tigers, on the other hand, face the somewhat more formidable White Sox. Well, someone has to win the Central division. Ultimately, this will be a footnote; the Yankees, Red Sox, and Angels are all singificantly more impressive teams than either the Tigers or the Twins.
UPDATE (10/3): Nope, we lost the first game to Colorado by one run, with plenty of missed opportunities to go ahead. Fortunately, St. Louis and Philly have both been losing two. Now we have only two games left, but we can still lock up homefield if we at least take the series.