I sent an email to Disney about this and here is their response:
Thank you for contacting WALT DISNEY WORLD!
Disney magic meets Disney music in a new 3-D film spectacular debuting in 2003
at the Magic Kingdom Park here at Walt Disney World Resort. The attraction will
be opened to guests for a sneak peak on September 30, 2003. The Grand Opening is
scheduled for October 8, 2003.
"Mickey's PhilharMagic" will star Mickey Mouse, Donald Duck and as well as Ariel
from "The Little Mermaid," Aladdin and Jasmine from "Aladdin" and Simba from
"The Lion King." animated in a way they've never before been seen: grand,
glorious, in-your-face three dimensions. This will be set in the PhilharMagic
Concert Hall, which replaces "Legend of the Lion King" in Fantasyland, the
eye-popping 3-D experience will unfold on one of the largest screens ever
created for a 3-D film, a 150-foot-wide canvas. Complete with in-theater
effects, the attraction will immerse guests in the richly animated world of the
Disney characters.