I found this on another website, certainly doesn't give us a date, but sounds "official" which is good considering we keep hearing this is a rumor...
"Begining Spring 2006, the Character Dinning experience will be back in Disney-MGM Studios for breakfast and lunch at Hollywood and Vine Restaurant. The new Character Dining Experience will be introduced with Buzz Lightyear, Mr. Incredible, Sarge and many other of your favorite Disney/Pixar friends. The Fantasmic! Dinner Experience will still be available for the dinner meal period."
And I found this too...I hope this is NOT true...
"They are aiming for starting the Character Dinning at H&V on June 2nd with the official start on June 4th. If the Disney/Pixar Character Dining is very popular for Breakfast and Lunch they will look to extend it to Dinner and move the Fantasmic package to another restaurant. This all (of course) is subject to change. After all, Entertainment was aiming to start in Jan/Feb but due to Character scheduling and Entertainment Contracts they kept having to push it back."