NASA Spacecraft Data Suggest Water Flowing on Mars
nasa.govNASA -- The happiest $0.005 of my tax dollars.
I love how the NASA administrator uses the opportunity to remind everyone of the goal to send human explorers to Mars.
Another discussion here http://news.ycombinator.com/item?id=2847028
I am glad that one of the current rovers wasn't in a position to have water wash over them. Especially salty water which is very conductive. That would be like 'instant death' for a robot probe.
Of course all of these things could have been discovered and analyzed much more quickly and definitively with a person present ...
The Mars' circumference is ~13000 miles / ~21000 Km. If the landing site is on the correct side of Mars, the astronauts have to travel, let's say 2000 miles / 3000 Km, without roads or gas stations. So probably in the fists expeditions the persons will explore only the neighborhoods of the landing site, and will not be able to travel to the interesting sites.
The analysis in the OP was from an orbiter, not a lander. The chances of landing a crew near such a site by chance seem low. And it would not happen this decade anyway. You need unmanned surveys to determine if and where it would be worthwhile to send a crew.
http://www.ustream.tv/nasajpl2 <-- live press conference