I saw this today in the Sharper Image catalogue. Lots of people will have, at least, seen one of these now.
CBGs must be getting more exposure now.
Turnbuckles come with two bolts. I have several that have eye-bolts, but other bolts are available. One of the bolts has left-handed threads. It works well as a bridge, since the angle of the threads lines up with the angle on the bridge. I've had problems with right-handed bolts where I need to files grooves in the spots where the strings should be to keep them in place.