HCI 2.0?: usability meets web 2.0

The web has already dramatically changed society, but the web itself is changing. Web2.0 sites mean that users have become the producers of content and the designers of each others' viewing experience. Technologies such as AJAX combined with public Javascript libraries have allowed applications to be deployed that once would have required extensive programming. Open APIs and mashups make it difficult to tell the difference between a service, and application or a web page. So what are the challenges for HCI when every user is designer, and every menu a different behaviour, when experience outranks efficiency, and connectivity replaces consistency?