Honestly, I consider Stephen Hawking to be the smartest man currently on the face of the planet. He figured out that Black Holes existed long before we were able to prove he was right, and now we know for a Fact that there is a Massive Black Hole in the center of our Milky Way Galaxy (how did J-Lo get way out there? LoL)
Since I'm a bit of a nerd about such things, I feel I have to correct you on this Hawking did not predict black holes. The idea was suggested as early as the late 1700's, and was "proven" before Hawking came along (a good deal of the credit goes to Einstein's general theory of relativity). I say "proven" loosely, because even today they haven't been proven to exist, although there is a lot of evidence to suggest they do. It's very hard to prove something exists when it is impossible to directly observe. Similarly, super massive black holes in the center of galaxies is not "proven" but the evidence highly suggests they exist.
Hawking's contribution to black holes is that they are not, in fact, completely "black." They actually emit tiny amounts of radation (called Hawking Radation). He also made some other significant contributions, but those are way over my head
All that aside, I agree, if he isn't the smartest human alive right now, he is pretty darn close. He is just amazing. And what makes him even more amazing is that, as Blaze of Glory said, he can be wrong. Not only that, he admits it that he was wrong, which is the really impressive part. Too often people insist that they are right, even if the evidence is to the contrary; because they don't like to be wrong.
I've only been able to watch some small clips of Into the Universe so far, but they were certainly interesting.
EDIT: For those interested: