Highly unlikely to be a completely different type of life
The discovery appears to be related to work at Mono Lake in California (which is very high on the scale of nought to awesome) where bacteria have evolved to handle high concentrations of arsenic in the water by substituting it for phosphorus.
On Earth any arsenophiles are likely to have once been regular bacteria that found themselves in a place where arsenic is unusually abundant. But what it means is that there might be a place in the Universe where life stumbled upon arsenic before phosphorus purely because it was locally more abundant.
This wouldn't be the first time a radically different biology has been found on Earth - the hydrogen sulfide based ecosystem of thermal vents is a good example - and there too, it was conventional life evolving into a new form because of a local surplus of sulfur.