From Derek van Vliet on Blog Herald
"It was a breakthrough year for social bookmarking. Several big new players burst on the scene. Participation in social bookmarking sites exploded. Social news sites got their foot in the door of the most mainstream news sites on the web. Social bookmarkers saw green in a variety of ways.
And for 2007: "... there is still plenty of room for growth in social bookmarking. While it certainly has its foot in the door of the mainstream, it is not yet a mainstream source of news [...]"