I suspect that the orbit of Daphnis isn't perfectly aligned with the ring plane. When it dips below (or rises above) the ring plane, its gravity will pull ring material with it. That is almost certainly the reason for any "vertical structures".
Of course, these "vertical structures" aren't monoliths, or tall spires. They are streams of material that are being gravitationally perturbed from
the main ring plane. Notice how the "ripples" in the ring structure are on the outside ahead of Daphnis, and on the inside trailing it? That is a
perfect demonstration of gravity at work.
[edit on 10-8-2009 by Mogget]