Pal Mickey ran off of a system where points throughout the park would broadcast park news using IR or similar technology. The nose on the mickey would read the signals and inform the family carrying it that it had news through laughing, shaking, and saying "oh, gosh!" Pressing Mickey's hand would have him say the information, such as "Buzz Lightyear's Space Ranger Spin has a very short wait! Ha Ha!" If it didn't have any news, it'd play trivia games or tell jokes, with one input on its chest and one on it's hand for the games.
The system was shut down in 2014, rendering all Pal Mickeys non-functional, outside of the games and trivia.
Some further history was present with the project, but that's what I remember from my childhood and a bit of Wikipedia I'm remembering from a few weeks back.