Like fivecups I'll wait and see....especially since:
The researchers "have coaxed a microbe" [/U] to build itself with arsenic in the place of phosphorus, an unprecedented substitution of one of the six essential ingredients of life
So it needed interference from humans - so even if validated all it will prove is that with outside interference form clever scientists the microbe did something out of the ordinary.
The following quotes form the original post are also interesting:
"Then the team started force-feeding the critters arsenate, an analogous form of arsenic, in greater and greater quantities."
"lot of work is needed to conclusively show exactly how the microbe is using arsenate"
We'll wait and see...