Cassini and the F rings of Saturn

At www.jpl.nasa.gov/news/news.cfm?release=2012-111&cid=releases_2012-111 images from the Cassini spacecraft show strange half mile wide objects pushing through Saturn's F ring with glittering trails following them (composed of ice from the ring). It seems the F ring is more dynamic than previously considered – see also www.nasa.gov/mission_pages/cassini/whycassini/cassini20120423.html for images and videos of the mini jets and other strange behaviour.