From the article: “Methane is a product of biology. For methane to be in Mars' atmosphere, there has to be a replenishable source”.
From http://en.wikipedia.org/wiki/Lakes_of_Titan :
The lakes of Titan, a moon of Saturn, are bodies of liquid methane that have been detected by the Cassini space probe, and had been suspected long before.
Why would methane be a product of life on one body and not on another? What is special about Titan?
Most probably, a big chunk of the oxygen in the atmosphere comes from last month's photosynthesis - we use it to make CO2 and green stuff converts it back, so, it's always brand-new oxygen we see. But free oxygen indicates a far more active biosphere than lots of methane would and I get your point - methane makers are much lower profile than oxygen makers.
As for Titan being covered with life... We really don't know if the lakes we see from space aren't giant amoebas waiting patiently to eat any humans that land on their beaches and just cleverly pretending to be lakes. ;-)
I fully expect us to find organic life on another planets sooner or later. However, I have my doubts about intelligent life. They could very well be less technologically sophisticated, in which case it might do more harm than good to interact with them (cf. Prime Directive).
Intelligent species tend to kill each other off. Note that we aren't the only hominids. Note what we are doing to the most intelligent of our cousins. Note what we did to the Neanderthals.
Since no active volcanoes are around, the article posits the more likely explanation is the microbe one. Not sure the half life on methane. Could this methane be lingering from whenever volcanoes were last active? If so, the more parsimonious explanation is the volcano one. If the half-life of methane is too fast for the methane detected to be left-over methane from ancient volcanoes, and if further we are quite certain there are no active volcanoes there now, then perhaps the most parsimonious explanation for the methane would be methanogens living beneath underground ice. If we can rule out the volcano theory, then the next step would be to send Bruce Willis over there to drill for methane and the methanogens that produced it.
Methane doesn't come from volcanoes, or from organic life; it comes from primordial deposits of hydrocarbons from the formation of the planet, released by heating of the deposits or sublimation, or whatnot. If there is life, and it is carbon based, then it subsists on these deposits and the evolved methane might be a waste product. I think the speculation is way off in the stratosphere here. I think further analysis is called for before drawing any conclusions.
