3 out of 4 18-24 year olds oppose spending money on sending men to Mars
http://www.nasawatch.com/archives/2006/12/aiaa_space_expl_2.html#more
The current numbers are pretty much like I guessed them to be - most people born after Mariner IV definitely do have any illusions about an Earth-like Mars.
They support Mars rovers (as we casn see from the number of internet hits), but not manned flight to Mars.
It's interesting that in contrast to this about 2.3 out of 4 18-24 year olds supported returning to the Moon.
Of course, the real question, "Should NASA deal with the impact hazard?", was ducked again by those paying for the polls. But that's okay, there was a poll taken last Christmas that pretty much decided that one.