Rashmi Sinha writes: “Flickr is the quintessential Web 2.0 application. Its data and metadata is contributed by its users; while the interface is its own. Its API’s are used by developers who tend to use its data, but not the interface (such as Mappr, Color Pickr).”
There is a nice slide which captures the shift from Web 1.0 ot Web 2.0.
