Simply: the designer is now responsible for facilitating community.
Digital Web Magazine - Web 2.0 for Designers: "In Web 1.0, a small number of writers created Web pages for a large number of readers. As a result, people could get information by going directly to the source: Adobe.com for graphic design issues, Microsoft.com for Windows issues, and CNN.com for news. Over time, however, more and more people started writing content in addition to reading it. This had an interesting effect—suddenly there was too much information to keep up with! We did not have enough time for everyone who wanted our attention and visiting all sites with relevant content simply wasn’t possible. As personal publishing caught on and went mainstream, it became apparent that the Web 1.0 paradigm had to change."