Why is the assumption that it is an actual cylinder?
Why couldn't it be a light streak of an object? Were these images time exposures?
That is how the recent moon in the G ring was found and imaged:
http://www.nasa.gov/mission_pages/cassini/media/cassini-20090303.html
Is there a reason people here are saying it is actually cylindrical? Or is this a
misinterpretation/wish fulfillment?
Going speculative here, would Saturn's rings be the best place to hide a spaceship?
At the least I think you would constantly have to be on your guard against getting
hit by ice boulders. And an old artifact would probably have been battered into dust
by now.