I can't remember the last time a movie had an intermission in a theater. I vaguely remember Monty Python and the Holy Grail had one, but was barely 3 minutes.
I think this does add to the epic nature of a blockbuster-style movie. Also, I can see concession stand sales skyrocketing.
2001. I saw it this fall at IMAX. It was a afternoon screening and it was just me and 6 or 7 other people. I guess it was all of our first time seeing a movie with an intermission because we all looked at each other after a few minutes wondering how long it would be.
I think it was about 10 min.