He arrived at Harvard in sept 2003 and the next week started to write code for "course Match" and then went on with Facemash...
1000 hours is around 20 weeks if you put 50h/w, less than 6 months.
TheFacebook launched on feb4 2004. So 1000 hours that may well be it or even more in the case of Facebook.
Search for ZuckNet: http://www.newyorker.com/reporting/2010/09/20/100920fa_fact_...
What he created was a decent web app that began superbly positioned and then expertly skippered it into the true golden market position.
The genius ranged from business to social to UI with programming ability being a distant if important factor.
And that in many ways does contradict the 1000 hour thesis - he could have had experience in building great web apps beforehand. He could not have gotten experience building billion dollar companies before hand - but he did well (however much I might find Facebook unfortunate on various levels).
RISC?