After watching Usain Bolt in the Olympics, I think 9.50 is possible.  It was amazing ... he's run only a few 100 meter races in his career ... he didn't get a perfect start .. his left shoe came untied ... and he slowed down in the last 20 metres ... but he still ran 9.69!  A commentator said that, by slowing down, he threw away a 9.59.

I've seen other races by Bolt where he tried harder than this.  When everything goes right, Bolt is going to change everything.