So, presence of oxygen and methane aren't necessarily indicators of life because "that makes assumptions about what life is", but stating that life must result in a huge majority of specific-handed molecules doesn't?
I'm wondering how likely this is to work over interstellar distances. Especially, given most (if not all) extrasolar planets have been detected through indirect means (see <a href="http://en.wikipedia.org/wiki/Extrasolar_planet#Detection_methods" rel="nofollow">http://en.wikipedia.org/wiki/Extrasolar_planet#Detection_met...</a>) rather than direct imaging.
Though I haven't read the article, but if the title suggests that life is limited to what we observe on Earth, then either we are defining life that way (and by definition we would only have it on earth-like objects) or have taken a very narrow view of what life is. Life is a very fuzzy concept, every researcher, every journalist defines it in his own way. Does life have to have carbon? Does it have to wiggle?