Why Tumblr Won't Tumble Like MySpace

Tumblr just hit a big milestone: 20 billion monthly pageviews. That's impressive for the blogging site, run by youthful CEO David Karp. But if you're familiar with older Web communities like GeoCities or Myspace, you know how traffic-driven success can be fleeting. GeoCities scored a $3.5 billion buyout from Yahoo, only to slowly wither. MySpace's users fled to Facebook, a competitor it used to...