Patterns for building social network type applications?

Question

I need to design / architect / develop a web based social network type application.

Basic functionality:
- users create accounts on the system
- users agree to

Answer 1

In the end it looks like Elgg or Dolphin might meet our requirements. These appear to be PHP frameworks for rolling your own social network. I looked at the Facebook platform but nowhere did it clearly explain just what it is - it appears to be the facebook code but perhaps it is only the code for an addon API or something.