From getthebigpicture.net:

"To celebrate the 25th anniversary of Back to the Future, AMC Theaters is bringing the film back to the big screen next month for 2 special showings.

You can see the film on Saturday, October 23 at 12:30pm, or on Monday, October 25 at 7:00pm. AMC says they have 158 screens for you to choose from. While the Saturday screening is probably more convenient for most people, the Monday one is a bit more special if you're a big BTTF fan: October 25th is the day on which the film begins (while the first time travel actually occurs on the 26th, since Marty meets Doc after midnight that evening). So in a way that's a good day to celebrate it. On the other hand, the movie was actually released on July 3rd, 1985, meaning that we're a few months late to be celebrating its actual anniversary. Depending on how you look at it.

You can get all the info, and search for a theater in your area that's participating in the event, by checking out the announcement on AMC's website.

The film shown will be a digitally remastered version, likely the same one from the forthcoming Blu-Ray release. As if that weren't enough reason to go, AMC says everybody in attendance will get a Back to the Future poster just for showing up, and there will also be "special movie-related giveaways prior to the movie as a part of the experience."

While I think this is a pretty cool thing to do, and I'll likely attend myself, I actually think it'd be cooler if they'd just show the whole trilogy. It's nice to get a chance to see a movie like this on the big screen—especially for you youngsters who didn't get to do so back in 1985—but I think things like this work even better if you can make an event out of it. Dedicate a whole Saturday afternoon and just marathon all three. But this is still cool, too."