The swimming portion of the 2012 London Olympics is nearly over, and with it—if you believe him, which I don't—Michael Phelps's career as the most decorated individual Olympian who ever lived. Friday Phelps finishes off his individual race card with the 100m butterfly—some time around 1:30 live, and in primetime on NBC if you can avoid being spoiled. He'll finish his career proper (theoretically) in the 4x100m relay shortly afterward.
Phelps, who will be 31 in 2016, when he will absolutely not be competing in the Rio Olympics and will be, I don't know, doing something else instead, won six gold medals in 2004, added eight more in 2008, and has two more so far in 2012, to go with two silvers. For most people, this would not be a career-ending disappointment. But most people aren't out-medaling medium-sized countries in good years, so I suppose a certain letdown is understandable.
In any case: Make sure to catch Michael Phelps's last two races Friday, because they are absolutely for sure his last Olympics races ever in London in the year 2012.