I think the Wachowski brothers realize that The Matrix phenomenon might just be their one-hit-wonder, and it seems like they sure are doing a lot to extend the franchise beyond a simple three movies… They’ve actually written everything you see below, with the exception of five of the Animatrix stories.

Matrix Timeline:

• The Animatrix was sort of a prequel to the Matrix series.
  

• The Matrix
  

• The Matrix Reloaded
  

• Enter The Matrix was loaded with over an hour of live action footage shot specifically to fill in some backstory for Reloaded.
  

• The Matrix Revolutions
  

• The Matrix Online plans to continue the story indefinitely.
  

This chat transcript with Jason Hall from Monolith says it all:

“The Matrix Online is the true continuing story of the Matrix franchise. Larry and Andy oversee it personally and the story will continuously evolve. We have a whole team here that will be doing nothing but adding to the game on a monthly basis. We are not messing around with this. This game is going to be like no other.”