This is a great little project that I just completed. The programming is the cool part. You just go to their website and they have a little javascript page that you can type in your message. You set you Blinky to receive mode and it programs by blinking parts of the screen. The Blinky has two tiny light receivers that detect the flashes on the webpage. You can program any message up to 253 characters. The hard part is waving the Blinky back in forth the correct timing to read the message.
It was very easy to assemble. The only compliant I had was they combined the build instructions with the Blinky Grid. Not a big deal, but it did confuse my eight year old son for awhile. For early beginners this could be enough of a problem to cause a fright.
I purchased my kit from Maker Shed, but they do sell them directly from their website. All of their projects are Open Hardware, so you can build on their ideas.
Here is a link to the programming page. http://www.wayneandlayne.com/blinky_programmer/
I plan to show this to the students at our schools technology night. I ran the programmer from my iPhone and it worked perfectly. I wonder if I can download their javascript page and run it offline. I may try that in the future.