In case you missed the first part on 4/3/08, here are parts I & II of a New York Times article by Errol Morris on re-enactment in documentaries. His new film, Standard Operating Procedure, is opening on April 25 (Sony Pictures Classics/Participant Media). 

Part I: http://morris.blogs.nytimes.com/2008/04/03/play-it-again-sam-re-enactments-part-one

Part II: http://morris.blogs.nytimes.com/2008/04/10/play-it-again-sam-re-enactments-part-two