What is Web 2.0?

I'm in San Francisco at the O'Reilly/Battelle Web 2.0 conference, where the central question is what is it?

In a back-to-back lineup this morning, Stewart Butterfield and Dick Hardt, in less then 10 minutes each, spoke volumes more than all other folks combined yesterday.

Stewart tells us Flickr is seeing the daily world through others' eyes, then adding our own.

Dick tells us Sxip is having the ability to verify yourself, in simple and open ways, through others' eyes.

Simply for me, Web 2.0 is coordinating and experiencing the world through others' eyes, then adding our own.