What is/isn’t Web 2.0?

O’Reilly have a nice article on What is Web 2.0 and Jason point out The top 10 things that aren’t Web 2.0.

PJ Heyett seems to know exactly what web 2.0 is . He says it is;

• pretentious
• oversized fonts
• pastel colors
• buzzwords
• featureless user experiences
• overly friendly and self-important copy
• acronyms

Update

Here is another funny Web 2.0 Checklist

• Give us your email address, we’ll let you know when it’s ready!
• Public -beta- alpha
• Tags
• Feeds for everything
• Built with Rails
• Sprinkled with Ajax
• Yellow fade
• Blue gradients
• Big icons
• Big fonts
• Big input boxes
• REST API
• Google Maps mashup
• Share with a friend
• TypePad blog for a peek inside the team
• Feature screencasts (thanks, Waxy!)
• Hackathons for new features
• Development wiki
• Business model optimized for the long tail
• It’s Free!/AdSense revenue stream