The "arsenic life forms" are really just bacteria they found in a lake where there was lots of arsenic, then they weaned it off of phosphorus and onto arsenic. It never even fully let go of phosphorus.
Still a cool thing to discover, and it does change the possibilities of life, but it was created, not discovered.
http://www.nytimes.com/2010/12/03/sc...er=rss&emc=rss