A friend of mine asked me today what all the recent talk about "Web 2.0" was about. Knowing that he was familiar with linux, my response was "chmod 777 web". He understood.
Update: Just continuing on the above thought...
There is something more fundamental going on right now. The web is becoming more hackable.. in the good sense. People are starting to realize that the web is more than just a publishing medium. It's a place where you can (or should be able to) actually do stuff. Web sites that let you do stuff are more important than web sites that only let you read stuff.
In the past, companies thrived by providing as many people broad access to as much information as they could. Today, everyone is faced with having too much access to too much information with very few good ways of managing it and using it. In the past, the only motivation a typical company had for luring you into their website was so they could show you advertisements you didn't want to see or try to sell you something you didn't want to buy. Today, many of those same organizations are trying to figure out other annoying ways of making those same annoying advertisements come to you even though you still don't want to see them. Smart companies will take a different route. Smart companies will provide their users with something to do; something that is of value to the user; something that the user will become loyal to; something that the user will become a part of; something that the user will respect; something that the user will be willing to pay for.