How to use UDP with the Arduino

In reference to a previous post of mine, I have decided to utilize the UDP protocol.

Now the question is how to get started. I'll be using an Arduino Duemilanove with and Ethernet Shield that will be attached to a local computer (this computer controls a submarine). Ultimately the Arduino package will become a remote from which to control the submarine from on a ship's deck rather than below it.

Is there reference material available on or offline that I could use to learn about UDP programming? Can anyone give any hints, suggestions, or tutorial site links that would help?