There are 368 drive-in theaters still showing films in the U.S., down from 4000 in the 1950s. I visited one during off-season in Wellfleet, on Cape Cod, a couple of years ago and tried to take photographs. Unfortunately, even with a wide-angle lens, it's hard to capture the magic of the screen. The slideshow here does a much better job than I managed to--probably because the photographer shot at night when the screen was lit up with the film.
The article from the New York Times appeared in the Business section of the paper--which means it gives a rather odd perspective on capitalizing on nostalgia (and there's precious little about the hanky panky that drive-ins were notorious for--at least as I remember from my high school years!): "Though far from their 1950s golden era, some drive-in theaters are going strong. Movie lovers are drawn by the low-cost tickets and an outdoor liveliness that multiplexes can’t match."