According to the Shifted Librarian and Entertainment Weekly, we can expect two and a half new Matrix movies. The videogame, Enter the Matrix, will have over an hour of film shot while making the two feature films. The story will be independent of the movies and will intersect with the film's plot. So you'll have to play the game to understand parts of the movie and vice versa. Another interesting fact is that the game cost $20 million to produce, which is four times the cost of the usual high budget video game.
Obviously, I haven't played the game, but I am now really excited about these movies. The Wachowski brothers really know what they are doing. Between the movies, the videogame and the Animatrix, this is going to be an amazing new experience.