The filmmakers of Black Swan have been discussed for the choice to shoot much of the film on 16mm stock, as well as some coverage being shot on the Canon 5D and 7D DSLRs (see IMDB tech specs). But I’ve seen very little coverage of the visual effects in the film, which you may be surprised to learn are rather extensive, including full-head replacements for a number of Natalie Portman dancing shots. They are also very subtly and tactfully executed. Here’s a behind the scenes video that shows clean plates, followed by composite and VFX plates…
There’s also some discussion currently on the quiet downplaying of the role of Portman’s body double, Sarah Lane, who did much of the ballet in the film.
UPDATE: Apparently, the film editor counted scenes with Natalie in them, and she actually did 80% of the dancing that appears in the film. More info here.