I'm pretty sure that Prometheus is tidally locked to Saturn - in the 2 or 3 available close-up pictures, it's long axis points Saturnwards. Although if it is tumbling in orbit, it would be easier to imagine this accounting for some of the F rings kinks and braids.
If the mission is extended in 2008, it would be fascinating for Cassini to drop into orbit close to the f-ring's outer edge and study the interaction between it, Prometheus, Pandora ( the outer shepherd moon ) and the two new moons or clumps discovered either side of the ring by Cassini. I imagine that from a range of 1000km or so, the ISS would be able to resolve individual ring constituents down to the size of a family car.