The dominant question popping up in a pragmatist's mind, observing the Web 2.0, is: how come people get so much free time in an increasingly hyper world? With the amount of blogging going on, either half of the literate population is procrastinating or the sales of Red Bull has to be booming.
Either way, even a child knows, these days, that it's all about content. If you got content - you got audience, with which comes influence, network effects, possibly money and vast amounts of bloated ego.
The thing about content is - presentation is every bit as important as the substance. Therefore, it is no surprise that the boom of Web 2.0 was inevitably followed by the revolution in the user-interface aesthetics.
The rarely addressed, yet important feature of the user-interface design is - scalability. If scalability for a software system means its ability to take brutally high user traffic without major changes to the source code, scalability for a user-interface means the ability to display vast amounts of content with the same crispiness which it handles just a handful of entries with.