Twitter couldn’t. Google couldn’t … By Farhad ManjooPosted Thursday, Dec. 3, 2009, at 5:20 PM ET Nearly a year ago—in the course of cajoling people into joining the ubiquitous social network—I marveled at Facebook’s astonishing growth rate: The site had just signed up its 150 millionth member, and about 370,000 people were joining every day. [...]