In know that people’s eyes glaze over when they see the term "Web 2.0" bandied about, but I still think it’s useful in describing a set of interconnected technologies and activities. Here’s an earnest attempt to define Web 3, where Vin Crosbie writes of sites like EveryBlock. He’s got a pretty good example of what he means here:
The first is when people in a community wonder what’s happening when
they hear their town’s firehouse alarm ring. The Web 1 solution is to
publish a professionally reported story, with audio, video, and text,
once the alarm is over. The Web 2 solution is to provide a forum for
citizens in the town to speculate immediately about what’s happening.
The Web 3 solution is to do all of those things, plus wire the town’s
911 response reporting systems to local media companies’ or the
municipality’s Web sites so people can immediately and accurately know
what’s occurring.