I never hear anyone talking about this, so I don't know if it is still being done, but we dined for the first time at California Grill (atop the Contemporary) in 2001 and while we were eating, the waiter came to our table and asked if we knew of any little girls that would want to start the fireworks. Of course my DD is sitting right there, smiling. They took her to the podium by the elevators and they made a very big deal out of the exact timing, and showing her which button to push. I think the control to dim the lights in the restaurant was also there.
At that moment the lights dimmed, the music started playing and the fireworks started. It was so magical! We returned to our table to enjoy the show, and they presented DD with a certificate stating she started Wishes with the date, manager signature, etc.
When we were leaving (excellent food and service, BTW) I spoke with the manager alone for a second, and kind of joked about"'Haha, yeah, like she really started the fireworks! Wink, wink!"
He swore ( well, not swore, but you know what I mean) that she did indeed start the fireworks, and this was not in front of DD. He said that it sends the signal, or something like that. I will say they make a huge deal about the time, there was a digital clock counting seconds next to the buttons. I still think he was just trying to extend that Disney Magic, and I appreciate it!
We told some friends of ours about it, and several months later they were there, had the same waiter as us, and were chosen.
My DD still talks about it. For instance, at school last month she had to write "3 things" about herself. She wrote that she has only gotten "As" on her report card, that she loves to golf and that she once started the fireworks at MK!