Another one of these cases came out today:
http://www.dailyexhumation.com/index.php?subaction=showfull&id=1184974454&archive=&start_from=&ucat=&
Throughout history, there's been lots of these cases, but most of them are probably never discovered since most people never get their brain scanned during their lives.
Quick summary is people who are missing their brains can live normal lives. Most of them are kind of dumb, but there was a famous one who got a PhD in Mathematics from Oxford or one of those UK colleges.
Last time these brainless people were covered was around the time that girl in Florida with brain damage was put to death, saying she was a vegetable, while her mom and some experts said she was aware.
Whatever the case with her, the other cases show that your center of thought and consciousness is apparently not the brain.