Facebook is just a fad, says cynical half of America

Even if Americans "Like" Facebook -- more than 40 percent of adults log in at least once a week -- they don't necessarily think their love will last. Half of us believe Facebook is just a passing fad, according to an Associated Press-CNBC poll. Half also think the social network's $100 billion valuation (more than Ford or Kraft or Disney) is overblown. But how many people actually use Facebook may simply be a factor of age. While only 21 percent of senior citizens and half of baby boomers have Facebook accounts, two-thirds of Gen X'ers and a remarkable 81 percent of those ages 18 to 35 do. 81 percent? Put that in your news feed.