There's little doubt that Facebook is the biggest tech story of the last few years. Starting as a dorm room start up, Zuckerberg has managed to do what Microsoft, with all its wealth and expertise couldn't do back in the 1990s and build what is, effectively, a private web. Those who were covering tech in the mid 90s will remember that MSN was Microsoft's failed attempt to create a closed web.
Facebook is a global phenomenon. With over 550 million users, it accounts for a quarter of the page views in the United States and is visited more than Google. And if you think Facebook's growth is slowing - each day it adds almost half a million new users. If Facebook was a country it would be the third largest in the world and would be adding a city that's larger than Sydney each week. And considering that one-sixth of the world's population can't access Facebook, because of Chinese policy, those sorts of penetration statistics are all the more incredible.
Zuckerberg has achieved this and not yet hit his 27th birthday making him the youngest recipient of this award.