Keeping the poison in perspective

This week I was surprised to see that The San Fransciso Chronicle had a front page article about biochemistry, Mono lake bacterium seen as model for life in space. The article was stimulated by a paper about to appear in the journal Science, A bacterium that can grow by using arsenic rather than phosporous. Earlier in the week a teasing press release from NASA had stimulated all sorts of wild speculation on the internet.
This episode reminds me of all the hype surrounding the claimed discovery of "life on mars" about decade ago, which was actually the discovery of some "dead germ materials on a meteorite that may have come from mars" which later turned out to be have other possible explanations. Some commentators said the discovery presented profound problems for Christianity. I failed to see this, even before the evaporation of the results.
So what has been discovered this time? Basically what the title of the Science paper says. In the extreme conditions found in Mono lake it seems there are some bacteria which are quite different from most other living things on the planet, which are poisoned by arsenic. These bacteria actually use arsenic instead of phosphorous. Do such life forms exist elsewhere? Where they important in the origin of life on earth? Maybe, but we have NO evidence. So any claims about life elsewhere are pure speculation and not scientific.