Web 2.0 is all about remixing, not about designing. The best metaphor for web 2.0 is the DJ, not the composer. Web 2.0 is a product of remix culture.
When talking about what Web 2.0 is, it is useful to start out by talking about what it is not. Web 2.0 is not merely the creation of websites with heavy amounts of user-generated content (ebay, amazon, etc). User generated content was part of the plan for these sites from day one, and these were some of the first internet businesses.
Web 2.0 is also not simply the ability to create integrations between web sites or applications. My web statistics vendor (statcounter) has been in that game for several years, as have the friendly people at the google adwords program. A vendor gives me some snippets of code that I drop into my website, and my website talks to their website, displays some content of their choice, etc. This is also not new, not exciting, and not Web 2.0.
Web 2.0, as I’ve said before, is not AJAX, although AJAX is a useful tool to make web 2.0 apps.
Web 2.0 is not blogs and blogging. But mass quantities of user generated content (both on commercial sites like amazon and blogs alike) set the stage for Web 2.0 by providing a moral pretext for remixing. If the value of the content is created by we the people, then we the people should be able to take that content back and build new things with it. And blog software created a software architecture that was remix-friendly, exporting rss and pinging central sites by default, and providing plugin APIs that any php newbie could use to build a remixed application.
The heart of Web 2.0 is about being able to remix and integrate without a negotiation, without permission even. It’s about being able to take an rss feed or an open API or data scraped from an XHTML website and grab that data, jam it together with another data source of the same kind, and build something new. Web 2.0 is about sampling, about mixing, about mash-ups. The web 2.0 hacker takes APIs and uses them the way a DJ uses albums, recombining disparate (already valuable) material into something fresh and new. Google Maps is an album. Craigslist is an album. Paul Rademacher is a DJ. HousingMaps is his latest production. Like scratching records, remixing is real-time: since you start out with most of what you need, projects take weeks, not years, to bear fruit.