ArduPower is a 6-port power strip controlled with an Arduino Uno and ethernet shield. You control and monitor each line via telnet. "
Unfortunately the link to the authors site doesn't want to play ball, so I am only guessing about what it does from the picture.
My initial thoughts are that this is an interesting product, especially with Christmas just around the corner when being able to control lights, decorations and other gadgets from a PC could be handy.
Using a old PC or laptop you could sync them to sounds, turn them off automatically at night or even vary the patterns. Come to think of it you could even allow them to be controlled over the web, although that's something I have never tried .
In the past you could control external devices from a computer using the parallel printer port or serial interface, but I haven't seen one of those on a new PC for years. Most interface projects tend to be USB based, however as this uses Ethernet it is going to have a much further range.
Judging by the authors name, I am guessing that this is not a UK based project, so we would have to design our own enclosure and connections to the mains. Personally this wouldn't bother me, but I am concerned that as Arduino is rightly popular with people who are new to engineering that we cold see some interesting, and potentially lethal, lash ups.
If you are considering trying this project, but have not worked with mains control before, then do yourself a favor and talk to an electrician first. Working with mains looks easy but it can bite, and quite often you won't get a second chance.
For full details (if you are lucky!) go to http://www.panu.it/ardupower/