And - crazy as it sounds - there was no really good way to share links. No Twitter or Facebook or Pinterst, so people had to use their blog. Or they could put it on Delicious, and others could subscribe to their feed via RSS (Originally there wasn't a way to view what all your contacts had bookmarked at once).
But Pinterst showed how the "social" side of "social bookmarking" should really be done.