If you go to the Light-0-rama link I mentioned, and prowl around a little, you'll find where you can download a demo copy of their software. Runs on a PC and connects to the controller via serial cable to an adaptor they sell; I think they have a USB adaptor, too.
According to what I read, any one of the controllers can accept the programming and then control the other controllers. They're daisy chained together using Cat 5 or phone cord. Each controller, and each channel on each controller, gets a unique address. That address controls an electric outlet into which you plug your string(s) of lights. There is a amgerage limit you have to watch, but it takes a lot of Xmas lights to build up significant amperage. Some of the things you can control for each channel are on, off, fade, shimmer and twinkle (shimmer is structured; twinkle is more random).
The actual programming interface is very much like a midi sequencer for music, if you've seen one of those. Each channel is shown on a separate horizontal line, which is divided into timed events. Each on, off, fade, shimmer or twinkle is an event. The sequence can be animation or can be tied to music. If you tie it to music, there is an interface to tap your mouse (or a key) in time with the music, with each tap becoming an event. For example, "tap tap taaaaap tap tap taaaaap tap tap tap tap taaaaap" Then, you go back and assign events to the time spaces, and do the same thing for each channel. Like all computer stuff, there are also other ways to skin the same cat.
According to their site, Light-o-rama completely sold out, this year. They're promising new hardware, wireless connectivity and pre-programmed sequences for next year. I think I'll plan to get in my order, early...