One fun thing about the tandem tallbike is that since tallbikes don't have brakes, the front person steers and the back person footbrakes.
The one pictured from May Day is "the Unridden". The top guy steers, the bottom guy's backrest is the turning steer tube. I think that after a certain height the top guy always has to steer, if you think about leverage you'll see what I mean. That bunk-bed tallbike shown from Iowa City is the same way, here's one from 1915 (click for video):
Another Minneapolis Scallywag bike (3 person):
Riding a tandem tallbike is really fun and very easy! The rolling mount is surprisingly not difficult.
