Last month, both Philip Roth and John le Carrè had apparently joined the microblogging service.
None of these were real (though Margaret Atwood, Jack Dorsey the co-founder of Twitter and, more embarrassingly, the New York Times public editor Margaret Sullivan were taken in by the hoaxes.)
The McCarthy account was created by unpublished novelist Michael Crossan, the Roth account by known Twitter hoaxer Tommaso De Benedetti. The le Carrè feed was quickly debunked and remains unclaimed, though De Benedetti previously faked an interview with that author as well with as Roth (his past exploits seem to hint that John Grisham and Toni Morrison hoax Twitter accounts may follow in 2013.)
Usually, enough people report the accounts (including the authors' own representatives) for them to be suspended, but not before a lot of readers and journalists look extremely silly for believing that they're real, and for reporting their often controversial tweets as quotes. De Benedetti, who has also impersonated politicians and foreign governments on Twitter, argues that he is attempting to show how gullible the media are when it comes to the micro blogging service.
Update: Today "le Carrè" tweeted (in poor English) that JK Rowling had died.
Link here for full piece.