Yes ... that began in 2003.
The winner of the all-star game determines home field advantage. If the NL wins they get it and vice versa.
The winner of the All-Star Game determines home field advantage for the World Series. For example, if the National League wins the first two games of the World Series will be played in the National League ballpark before playing the next three in the American League ballpark.
Whichever team held a better record during the regular season, holds home court advantage. Thus giving them home games 1, 2, 6, and 7.
As you know there can be 4 teams in the Playoffs, the 6 Division Winners and the 2 Wild Card winners from both the American and National Leagues. The team with the best record in either division will play the Wild Card winner for their league but if their Wild Card winner is in the same division as them then they'll play against the team in their same league who has the 2nd best record. How it determines who holds home field advantage for the Division Series and the League Championship Series is based on their Regular Season record but this only applies to the Divisional Winners, Wild Card winners can never have home field advantage during the Divisional Series or the League Championship Series. The World Series' home field advantage is as you know based on the outcome of the All Star Baseball game.
There is an MLB rule that states the League that wins the All-Star game has home field advantage in the World Series. Since the American League won the 2009 All-Star game, 4-3, they get home field advantage for the 2009 World Series.
2001
Unlike in the MLB, where the winner of the All-Star game determines which team will have home-field advantage in the World Series, there is no prize for winning the All-Star game in terms of basketball. It is merely an entertaining event.
Major League Baseball instituted a new policy this year, giving the home-field advantage in the World Series to the team from the league that won that year's All-Star Game. The American League won the 2004 All-Star Game, so the AL's World Series representative--Boston--gets the home-field advantage.
The best athletes of the National and American Leagues face off in an annual MLB All-Star Game to determine which league will have home field advantage during the World Series later that fall.
Home Field Advantage was created in 2000.
Nothing but the winning team gets home field advantage for the world series.
Best of 7 games wins the series. The league that wins the All star game gets home field advantage. Games 1, 2, 6, and 7 (if needed ) are played at the park of the team with home field advantage. Games 3, 4, and 5 (if needed) are played in the other teams park.