Ok, kids, you want to understand Web 2.0?
Just watch this. All you need is here.
[Update 20/11] As noted in the comments, the person at Nokia who uploaded the video has taken it down – if you try and play the video, you’ll see this text:
We’re sorry, this video is no longer available.
If you go to the page on YouTube corresponding to the address in the clip, you’ll see this:
This video has been removed by the user.