For those with access to Icarus, there is an informative paper in press that was just posted:

Titan's surface from Cassini RADAR SAR and high resolution radiometry data of the first five flybys
Icarus, In Press, Accepted Manuscript, Available online 24 May 2007,
F. Paganelli, M.A. Janssen, B. Stiles, R. West, R.D. Lorenz, J.I. Lunine, S.D. Wall, P. Callahan, R.M. Lopes, E. Stofan, et al.
PDF (920 KB)