Ahem, there is a difference between *evidence* and *proof*
Nick, surely as a scientist you understand the difference between "evidence" and "proof." The seepage gullies *are* evidence for near-surface liquid water on modern day Mars, just as they *are* evidence, assuming one accepts the non-liquied H2O arguments, for other putative fluids. The point is that the issue is not as cut and dried as you assert (i.e., near-surface liquid water is a "pipe dream"). Perhaps laypersons (here in this group and elsewhere) are dazzled by flat out assertions such as this and accept such ponitification as "fact", but the scientific community is another matter.
Alex R. Blackwell
University of Hawaii