Here's a video:
Step 1: Parts List
I used an Ikea Galant desk, which just happened to have the perfect frosted surface to diffuse the lights. That is really the most important part of the project.
Assemble the desk according to the normal instructions. We can easily work with the completed desk from underneath.
Arduino Uno Ethernet
Arduino Power Source (http://www.adafruit.com/products/63)
Addressable ws2801 or lpd8806 (I used http://www.adafruit.com/products/683)
Power supply for LED strip (http://www.adafruit.com/products/352)
peg board or foam core
100 zip ties
padded double sided tape
By the way, all my electronics for this version came from Adafruit.com. They were extremely helpful on their forums and I was able to get everything I needed in one order from one place. You can get one or more of the light strips and just connect them in serial.
Step 2: Arrange your lights
I used the double sided tape to attach the hinges to the desk and then bolted them to the peg board. The velcro keeps it closed, but provides easy access to open it up whenever needed. This was great for the Maker Faire, because I was able to show people the guts of the desk.
Step 3: Add the brain and connectors
The Arduino will connect to the lights using the ground pin and two other pins. pay attention to which pins you use because this will have to match the Arduino code. The default in the code is to connect the yellow Data wire to pin 2 and the green Clock wire to pin 3.
Once everything is placed, it is a good time to make your wire connections, by whatever means you prefer. I used RC servo connectors for the signal lines and Molex connectors for power. There were commonly available and easy to work with.
For the initial power connection to the lights I used a 2.1mm barrel connector with screw terminals. This matches the power supply in the parts list.
CAUTION: Both the Arduino and light power supplies use the same connectors. If you connect the larger power supply to the Arduino, it will be damaged. I marked the two connectors with different color electrical tape to make sure I did not do this.
Step 4: The Software
You'll also need to download and install the Arduino tools to upload the code onto the microcontroller. http://arduino.cc/en/Main/Software
Open up the code in the Arduino software and modify the required lines. You'll need to change things to correspond to your selected hardware. The entries are all marked in the code with the word "update" so search for that and follow the tips in the comments.
You'll have to change the MAC address to match your Arduino ethernet shield, the IP address to match your network, the number of lights to match your light strand, and the grid function to match your physical layout.
The grid function may be the trickiest. It takes an x.y coordinate and maps it to the numeric index of the light in the strand. Luckily some experimentation makes it very obvious which lights are which.
Now you can control the desk by requesting a web page. Just send it one of the accepted commands. You can find a list of commands in the code. The format will look like this: http://desk_ip/alert?ffffff or http://desk_ip/skype
Once you've confirmed that is working correctly, you can set up any scripts you want to send commands to the desk. I've included a couple of AppleScript files that can be used to trigger the lights from a Mac app like Mail. There is also a Growl style that shows how to get Growl to trigger the lights.
Remember that since you can control the desk over the network, these events can come from almost anywhere...servers, render farms, mobile devices, voip phones...whatever can request a web page.