So what is the web 2.0 ?

Tim O'Reilly's article called: "What Is Web 2.0: Design Patterns and Business Models for the Next Generation of Software" these are the changes at hand:

Web 1.0 --> Web 2.0
DoubleClick --> Google AdSense
Ofoto --> Flickr
Akamai --> BitTorrent
mp3.com --> Napster
Britannica Online --> Wikipedia
personal websites --> blogging
evite --> upcoming.org and EVDB
domain name speculation --> search engine optimization
page views --> cost per click
screen scraping --> web services
publishing --> participation
content management systems --> wikis
directories (taxonomy) --> tagging ("folksonomy")
stickiness --> syndication