Well, the slide has been viewed more than 18,000 times so far, but here are some highlights in text:

Tim O’Reilly, in summarizing a brainstorming session at Foo, lists the following attributes of a classic Web 2.0 company:

Attitude, not technology
The Long Tail
Data is the "intel inside"
Hackability
Perpetual Beta
Right to Remix (some rights reserved)
Software that gets better the more people use it
Emergent user behavior not predetermined
Play
Granular addressability of content
Rich user experience
Small pieces loosely joined  (web as components)
Trust your users

This is by no means a complete list, but it represents a way to think about what you build online (and, imho, offline as well.) And it reminds me of big thinkers like David Weinberger and Lisa Gansky. Web 2.0 isn’t new, but it’s now.