In the annals of the Make-a-Wish Foundation, there's never been anything as big as this.
A five-year-old boy named Miles, who lives in northern California, has leukemia. He loves superheroes, and his fondest wish is to be Batman. So Make-a-Wish put out a call for help from the citizens of San Francisco, where Miles' wish is to be realized in an elaborate set of stunts on Friday, Nov. 15.
They got more than they bargained for — 7,100 RSVPs on the website, and counting.
See also: Batman Goes Old School in 'The Dark Knight' 8-Bit Remake
The plan is for Miles to have an action-packed day around the city: rescuing a damsel in distress on a cable car, capturing the Riddler in a downtown vault, chasing the Penguin around Union Square, and finally receiving the thanks of a grateful mayor and police chief on the steps of City Hall.
Volunteers were needed to form large, appreciative crowds to witness Batkid's deeds, and urge him on in all those locations; organizers say they had no idea they'd be getting this many sign-ups. It may not be a world record for largest flash mob, but it is certainly the largest event the foundation has ever put on.
A number of supporters from around the U.S. have told Make-a-Wish they'll be flying to San Francisco just to participate.
Foursquare will be letting participants check in to "Gotham City" on the day. Several Facebook users set up a Batkid page. Make-a-Wish reached out to Twitter, and now the Penguin is taunting Batkid on his new account:

Other Batman-themed tributes are in the works, and it's possible Miles may end up with a comic book from DC Comics detailing his exploits.
Have something to add to this story? Share it in the comments.
Image: Make-A-Wish, Greater Bay Area