We've been following the progress of the discovery of methane in the Martian atmosphere for awhile now. First spotted by the ESA's Mars Express probe, the existence of atmospheric methane (which would be driven out of the air within 300 years) implies that Mars is much more lively than previously thought. Furthermore, methane is generally produced either through biological or geological phenomena; since we've seen no evidence for recent geological activity on Mars, a number of scientists are starting to seriously consider the possibility that Mars does, indeed, harbor life.
Space.com now reports that Earth-based astronomers at the Infrared Telescope Facility on Mauna Kea have confirmed the presence of methane in the Martian atmosphere, particularly over the equatorial regions thought most likely to harbor microbial life under the surface. As we accumulate more data about the cycles and amount of methane, we'll better be able to determine whether the methane comes from abiogenic geological sources. Discovery of life on Mars would give us our first look at a new ecosystem, and even a simple and primitive one would add enormously to our understanding of how planetary environments work.
If there turns out to be life on Mars:
Earth is no longer unique;
Life is likely commonplace through the Universe;
Martian life will have been found largely via James Lovelock's and Lynn Margulis' ideas of "Gaia".
What does that mean for the human zeitgeist?
The highest concentrations are equatorial, which is not what you'd expect (solar radiation will break it down faster at the equator than the poles), so the odds of life on Mars just went up.