Hi; I thought was a very interesting piece. In the same issue there is an article about Saltinibacter ruber- a bacteria (not an archaean) that lives in up to 37% salt.
http://www.pnas.org/cgi/reprint/0509073102v1

Bacteria can and do live in brine; Bacteria can and do live in acid; Bacteria can and do live in ice. The point is, while Mars now looks singularly sterile, extremophiles show that we do not know exactly where the limits fall on the evolution of life or its ability to survive. Mars may have been close to this limit and if it it did not cross it, it is still important to know how close Mars (and other systems) came to the boundary between living and dead. If life is fragile and evolves only within very discrete optimal boundary conditions, nothing would have happened on Mars. If the origin of life is very robust and evolves (but not necessarily survives) under many conditions including those that are very difficult, Mars may have been an incubator for primitive organisms or their abiotic precursors, and these will have left traces. Either way it should eventually tell us something very important about the basis of life.