Jackie Robinson Day is the annual celebration by Major League Baseball of the first African-American player to play in the majors. It began in 2004 and occurs every year on April 15, which is the day Jackie made his major league debut in 1947.
For the 2011 Jackie Robinson Day, Major League Baseball launched a website called I Am 42 (42 was the number Robinson wore with the Brooklyn Dodgers). On the website, current players, past players, managers, owners, broadcasters, etc, photos are montaged into the number 42 and if you click on each person, you can see a video of each person talking about what Jackie Robinson means to him or her.
In baseball Friday, the teams will all be wearing numbers 42 to honor Jackie as well. There are a full 15 games today, so no team has to postpone the wearing of their no. 42 jerseys. The official celebration is before the 7:05 PM game at Yankee Stadium and will feature
members of Robinson’s family. That site is chosen as the official celebration every year because that is the site (or now with the new Yankee Stadium, right next door) where Jackie played against the Yankees in seven World Series.