Curmudgeons has made a good post on using "the discovery of life" argument for going to Mars.
It's a little ridiculous to use the excuse that we are going to Mars to find some germs on a far flung rock somewhere. And so what if we do? What have we gained?
I think some people honestly believe that as soon as they do find Martian germs that Congress and the world will suddenly snap to attention and follow the barking orders of the space scientist elite. That may happen in Star Trek but this is reality folks.
Unfortunately what would probably happen if they did find even the most basic life on Mars is that enviro nutsos would immediately want to quarantine the whole planet for the sake of preserving the Martian ecosystem. Then others would be worried about astronauts bringing back a deadly martian bug to Earth that could infect the human population. The most probable outcome of discovering life on Mars sadly is that they would plant a few flags in the ground, head back home, and for thirty years space enthuasists will wonder why humanity hasn't done a thing since then.
The only hope I have with this new VES iniative is that NASA will be forced to allow more private industry involvement. Since Bush set a gap in between the shuttle retirement and the first flight of the new Crew Exploration Vehicle, it forces NASA to look at other providers to supply NASA with space transportation services during that time period. My hope is they will look to private providers instead of the Russians. Also since the focus is on returning to the moon there is the real possibility of setting up a permanent settlement there.
If we can't even colonize our nearest neighbour how do we expect to colonize another one thousands of times farther away?