Okay, Retroshift finally opened their doors for business.
Essentially it is a shift mount on a dedicated brake lever, that moves a downtube or bar-end shifter to the front of the lever.
For tandems this provide an interesting possibility of mounting a Retroshift on an STI or Ergo shifter which controls the Arai drag brake.
Over on the Classic and Vintage forum we've already started a campaign to get Retroshift to provide a service offering their shifter mount for vintage levers, as most of us over there don't want modern Tektro levers which is what Retroshift is currently using.
However, I think a fair number of us who use an Arai drag brake would consider adding a Retroshift mount to control the drag brake, both front and rear brakes, and shifting all without taking a hand off the handlebar.
I've always felt that downtube shifters and bar-end controls (even just for the drag brake) were dangerous on a tandem. Anything that requires removing a hand from the bars needs to be rethought.
If interested give Retroshift a holler and let 'em know you'd be interested in having a Retroshift mount on your Campy Ergo or Shimano STI levers:
http://retroshift.com/contact-2/