by Claudine Zap This past weekend, blockbusters " The A Team " and " The Karate Kid " did battle at the box office. But a surprising limited-release documentary about a fesity Joan Rivers stole a lot of the buzz. Can we talk? The comedian is the subject of " Joan Rivers: A Piece of Work ," and the documentary is getting glowing reviews : Roger Ebert called it "one of the most truthful documentaries about show business I've seen." Fans have also wanted a closer look.