Totally awesome, 10 strings of 50 RGB LED lights each:
Houston, we have a Christmas tree in space.
I just wandered across someone else using a FEZ to control these LEDs for another cool purpose.
That is one of “ours” (username andrejk)
http://code.tinyclr.com/project/196/ge-35-christmas-lights-individually-addressable/
I think the callange not in making LEDs turn on and off but in teh creativity in making them look amazingly in sync.
Thats why I posted it in the first place. Should have chosen another title i know.
That is exactly what i have been wanting to build. Thanks for posting 
Found more info on hacking the GE Color Effects G-35 led string, if interested.
[url]http://www.deepdarc.com/2010/11/27/hacking-christmas-lights/[/url]
Now to find the best deal where to get them.
That is a great tree - really nice animations. We just finished a Christmas project just last night. This is 3 Christmas trees with 50 LEDs each and a pvc pipe creating an over the top “swoosh” that has three star / snow flakes - all in sync. This project used a total of 267 RGBs with WS2801 chip run by a single poor little over worked arduino.
Here is a link.
Note: The rainbow / color changing window in the first part of the video is not the above mentioned installation, it was another project that uses a 5 meter strip with LPD6803 chip - still a work in progress as a permanent display.
@ hookedup Very nice!