Published online today in Geophysical Research Letters:

Chappelow, J. E.; Sharpton, V. L.
The event that produced heat shield rock and its implications for the Martian atmosphere
Geophys. Res. Lett., Vol. 33, No. 19, L19201
10.1029/2006GL027556
03 October 2006
Abstract

For without access to GRL, this was the subject of an abstract by the same authors at LPSC earlier this year.