Microbial Life Found in Hydrocarbon Lake
technologyreview.com
technologyreview.com
The problem that I see is not that life is delicate (we know it's not), but rather that we have never seen another form of life. That is, every form of life that we've found on Earth can be traced back to a single ancestor. Most of them use DNA/RNA, all use the same left-handed-proteins, etc.
What would really be amazing would be the discovery of a second independent form of life. The spontaneous development of life twice on the same planet would pretty much guarantee that the universe is teeming with it...
It might be less likely, as we (you, me, and a couple scrillion of our closest relatives) provide robust competition against any other types of life, which may, as you mention, need different chiralities of various molecules, and may have trouble digesting any portion of our biomass.
I suspect Earth is probably the most amenable place in the solar system for long term life because of a number of features:
* High ambient energy (temperature, non-ionizing radiation)
* Shielded from ionizing radiation
* High atmospheric and oceanic churn
* Stable geology
* Rich dispersion of minerals
Though you are right, the competition on Earth that a second branch of life would face is not insignificant...
The interesting thing in the article is the density they found: 10^7 organisms / gram.