There has been quite a bit of discussion here, on the possibility of this being a completely new type of life (no common ancestor with other life). That would have been mind-boggling amazing indeed - but from what I read, it sounded much more likely that what they found where an more or less ordinary microbe that have substituted phosphorous the chemically similar arsenic (and still have the same nucleic acids, base-pairing, ribosome, protein synthesis etc).

Looking at the press release from Nasa, this is indeed the case:
http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html

The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. In the laboratory, the researchers successfully grew microbes from the lake on a diet that was very lean on phosphorus, but included generous helpings of arsenic. When researchers removed the phosphorus and replaced it with arsenic the microbes continued to grow. Subsequent analyses indicated that the arsenic was being used to produce the building blocks of new GFAJ-1 cells.

It's still amazingly cool, but life as we know it is not falling apart =)