On the phpaddiction site today, there's part two of their tutorial looking at URL routing with PHP (started here in Part One).

With the foundation of the routing in place (from part one), they move on to bigger and better things:

• assign responsibilities (what needs to be accomplished)
• creating a standard command object
• interpreting the URLs and the parameters passed in it
• using this information to dispatch the correct commands

There's code examples through out to illustrate each point as well as one main one at the end to show how to put it all into action. Their script reads in the URL and sends the command along to the CommandDispatcher - check out this example page to see it in action.