From the Academy of Motion Picture Arts & Sciences web site:
The Academy of Motion Picture Arts and Sciences today announced that 15 films in the Documentary Feature category will advance in the voting process for the 84th Academy Awards®. One hundred twenty-four pictures had originally qualified in the category.
I'm mildly disappointed that Being Elmo isn't on the list but one can hardly argue that the film hasn't been successful. If you also enjoyed its Muppety goodness, you can always vote for it in the IFP Audience Awards.