The shock that is shown in what is known as the 'Works Performance' shock, which to the best of my knowledge is a Boulder made shock. It is an oil/ coil shock, that you can change the pre-load by disconnecting it from the swing-arm and turning the shaft. The connection between the shock and the swing-arm is a motorcycle chain master link. It is easy to take off and put back on (and just as importantly it is cheap and readily available- not some hard to get custom part).
I had one of these shocks in my Boulder Intrepid. I don't have any pics of it, but think of a Yeti Ultimate with a shock in the top-tube and a pivot at the chain stay/ down tube.
Boulders also came out with a Risse Racing Genesis, which is a simple air oil set up. There was also the option for an upgraded "Clyde-Glyde' model, which has a larger air volume, so it runs at a lower pressure, and tends to be a better shock over all.
The Works Performance shock had a plusher ride IMO, but the Risse was way lighter, and gave a firmer, more like a hard tail like ride. The Intrepid had 3.25 inches of travel, and the Starships have 3/4/5 inches of travel depending on which model you bought.
I have a Boulder Starship Ti, and think it is the best short travel bike Iâ€™ve ridden. I've ridden bikes that have twice the travel, but the Boulder still feels better (3" of good suspension is better than 6" of bad suspension).
Boulder is still around, though the site hasn't been updated in years. http://www.boulderbikes.com/
If you are bored look at look at the following bikes and test your retro knowledge and see if you can name all the parts