Recently, my friend's volunteer placement organization, Insight Argentina, was the subject of a documentary:
Insight Argentina: Volunteering in Argentina's Social Sector
Directed by Mimi Butler and funded by Jennifer Webster
The second half of the film focuses on ph15, a photography workshop founded by Martin Rosenthal for the children of the "Hidden City" - a slum on the outskirts of Buenos Aires. You can learn more here and here. The ph15 portion of the documentary begins at the 15:30 mark. You can watch the documentary full-size and choose scenes at Google Video. Visit Insight Argentina if you are looking for a South American adventure in social volunteerism.