The second film in the trilogy, The Matrix Reloaded, will appear in Imax theaters a couple of weeks after its May 15th debut in regular theaters. The third film, however (The Matrix Revolutions) will go down in history as the first live-action Hollywood film to open simultaneously in regular theaters and Imax theaters.
Another interesting note from the article is an upgrade in the Imax technology. Previous Hollywood films such as Apollo 13 had to be shortened to fit on a single Imax reel. Since then, however, the reel parts have been upgraded, and they now support a maximum length of 150 minutes.
Damage has mentioned this once before, but in case you missed it, anyone with broadband should go to the official Matrix web site and download the final theatrical trailer. I recommend donning adult diapers before viewing.