With the rovers on temporary hiatus while receiving new software I suppose we can discuss some of the results at the 2004 Lunar and Planetary Science Conference.

This report I found particularly interesting. It gives an experimentally determined evaporation rate of 1.1 mm/hr :

EVAPORATION RATES FOR LIQUID WATER AND ICE UNDER CURRENT MARTIAN CONDITIONS.
D. W. G. Sears1, 2, S. R. Moore1, 2, A. Meier1, 2, J. Chittenden1, 2 , M. Kareev1, and C. B. Farmer1 ,3, 4, 1Arkansas-Oklahoma Center for Space and Planetary Sciences, 2Department of Chemistry and Biochemistry, 3Department ofGeosciences, University of Arkansas, Fayetteville, Arkansas 72701, USA. 4Jet Propulsion Laboratory, Pasadena,
California 91109.
Lunar and Planetary Science XXXV (2004) 2112.pdf
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2112.pdf

Bob Clark