Here is some of the text from the Cassini site that explains these new images:
With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.
This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006. The full mosaic consists of three rows of nine wide-angle camera footprints; only a portion of the full mosaic is shown here. Color in the view was created by digitally compositing ultraviolet, infrared and clear filter images and was then adjusted to resemble natural color.
The mosaic images were acquired as the spacecraft drifted in the darkness of Saturn's shadow for about 12 hours, allowing a multitude of unique observations of the microscopic particles that compose Saturn's faint rings.
Ring structures containing these tiny particles brighten substantially at high phase angles: i.e., viewing angles where the sun is almost directly behind the objects being imaged.
During this period of observation Cassini detected two new faint rings: one coincident with the shared orbit of the moons Janus and Epimetheus, and another coincident with Pallene's orbit. (See The Janus/Epimetheus Ring and Moon-Made Rings for more on the two new rings.)
A side view of the rings.
Dark Roasted Blend has a nice entry on these pictures and the mission of Cassini.