OK, a follow-up here.

All of the news reports originated from a single source, Brian Berger at Space.COM. It appears he got it wrong. In fact Nature never did get a paper submitted. He probably heard from a friend who heard from a friend... He may have confused the LPSC talk below with a pending paper publication somehow.

Stoker & Lemke are real scientists and show up in Lunar & Planetary Science Institute notes going back at least a dozen years.

They are scheduled to give a brief talk at the 36th Lunar & Planetary Science Conference in League City, TX, March 14-18 (they're Monday 9:45am-10am - drop by and ask about it ). The abstract is here.

My take: it's interesting work, but unless there's more it's much too early to be talking about Mars. They don't appear to know anything at all yet about what they found at Rio Tinto, such as environmental parameters for survival and reproduction, nor what might affect methane production (i.e., what makes such microbes make a big fart ).