Storytelling across The Matrix
Salon.com has an article about how the storyline of The Matrix is distributed over several films, animated series, and the upcoming video game. It discusses what's special about this approach compared to other detailed fictional universes, such as Star Wars. You'll need to click through an ad to get to the article.
It also links to the development diary of Michael 'Saxs' Persson, lead programmer of 'Enter The Matrix'.