A few weeks ago I sat down with David Weinberger, author of Everything Is Miscellaneous , to talk about Wikipedia. When David asked me if concerns about Wikipedia quality persist, I noted that since 2005-2007, when a number of comparative quality studies were published, much of the criticism has moved to issues associated with biographies of living people. I noted that at the end of the movie Truth in Numbers , while the credits are rolling, the filmmakers ask the interviewees to look at their own Wikipedia biographies. People often find errors, or feel that the biography is unbalanced and hence misrepresentative. (This is what prompted Jaron Lanier's critique of Wikipedia). David adroitly noted that the only biography a person would not complain about is their obituary.
I'm not aware of any comparative studies of biographies of living people. I suspect this would be a more challenging task in that many of the biographies that Wikipedia has, would be about subjects that more traditional sources would not yet consider notable. Nonetheless, it would be an interesting study.
You can hear more of the conversation between David and me at Media Berkman .