User blog comment:Vel!/Call for math facts/@comment-5529393-20140730095802/@comment-5529393-20140730104529

The general consensus of the math community is that Perelman is the one responsible for the proof of the theorem, and that Cao and Zhu were simply two of many people who filled in details after Perelman presented his proof.

It appears that a crucial argument of the Cao/Zhu paper appeared in a previous paper by Kleener and Lott.

See for example http://en.wikipedia.org/wiki/Manifold_Destiny