Facebook CEO Mark Zuckerberg has learned to make safer prognostications. At this year's Web 2.0 Summit, he observed that the amount of information people share on Facebook seems to double every year — a claim he might be able to back up with data from his social network. Zuckerberg's Second Law will surely go over better than his first — the assertion, made as he launched new Facebook ad formats, that "once every hundred years, media changes." Zuck, how about this law? Once a year, a CEO has to come up with something impressive to say at conferences. (Photo by Brian Solis/Bub.blicio.us)