Yes, this is a geek post; deal with it! One of the major results the various Mars orbiters and rovers have been trying to work out is whether or not the red planet has ever harbored life, and one of the preconditions of life is a water supply. At least our kind of carbon based life, and there are good reasons why two planets in the same solar system would bear the same flavor of life. The most obvious two are:

1) Our planets condensed out of the same orbital dust cloud around our condensing star, and are therefore made from the same ratio of elements at the same stellar evolution stage, and

2) High speed impacts on either planet by rocks with enough kinetic energy to blast objects beyond escape velocity will tend to include any organic building blocks. Some percentage of those ejecta will end up raining down on the other planet, thereby sharing enzymes, RNA, DNA, and other life building structures between bio-zones.

With that as a given, it is exciting to find out they now have the evidence that Mars had water, enough to completely reshape the planet and generate clay deposits, as recently as 4 billion years ago. Since life on this planet started evolving 5 billion years ago, we had a clear billion years to cross-pollinate.

But there is one more detail that gave me the biggest grin of all about this; Did you notice that in each article the scientist reporting the Mars results was named after the ERB character John Carter of Mars? Is this going to impact on the movie? I am ready for that film!