WEB 2.0 Logo Design
The term Web 2.0 refers to a second generation of services available on the World Wide Web that lets people collaborate and share information online. In contrast to the first generation, Web 2.0 gives users an experience closer to desktop applications than the traditional static Web pages. (from wikipedia) Most Web 2.0 sites have a similar look and feel, you can see some of these striking commonalities in Ludwig Gatzke’s compilation of nearly 400 Web 2.0 logos. 
Stephen Coles of Font Shop has a great article that goes into depth on the design and especially the use of different typefaces in Web 2.0 logos. He classifies them in several categories, e.g “the softies” using soft, rounded typefaces that lend a modern friendliness to what might otherwise be a cold trademark, “the futurists” that use pixel faces, hard edges, and ultra simplified forms for a look that says tomorrow’s techno, “the classics” and “new classics”. He also says about the brands, “even more characteristic among these brands is their appearance. Web 2.0 sites nearly always feel open and friendly and often use small chunks of large type. The colors are bright and cheery — lots of blue, orange, and what we jokingly call the Official Color of Web 2.0: lime green.” Read the full article at FontShop.com’s blog
For more on Web 2.0 check out O’Reilly’s comprehensive article
Images courtesy of flickr.com