The Phillies finished up a 5-0 season-sweep of the Rockies with their 6-1 win on Wednesday, May 28th, exacting revenge on the team that swept them out of the playoffs last season. In doing so, the Phillies became the second team ever to sweep a season-series against the team that swept them in the playoffs the previous year.
The only other team to do this was the 1998 San Francisco Giants. After the eventual World Champion 1997 Florida Marlins swept the Giants 3-0 in the NLDS, the 1998 Giants went 9-0 against the Marlins in the regular season. Interestingly enough, this was the only team that the Giants went undefeated against that year.
Of course, it didn't hurt that the Marlins won only 54 games in 1998 and failed to win a game against the Reds, Brewers, and Yankees, as well as the Giants.
But the '08 Phillies and '98 Giants could have to make room for one more soon, as the Cubs are currently 3-0 against the Diamondbacks this year, after Arizona swept them in last year's NLDS. The Cubs and D'backs have three games remaining (July 21-23), so the pressure's on them to join this elite (or at least, selective) club.