It looks like Phoenix is finding results with chemistry analysis tests that suggest Martian soil could - or could have supported life. We have known for a while now that elements like magnesium, sodium, potassium and chlorine are all found in Martian soil. Now we also know that the soil alkalinity is comparable to that which we grow all kinds of plants in here on Earth.
There are more tests to be done, but these results could make growing vegetables in Martian soil a reality one day. It also makes it more conceivable that some kind of life may one day have existed on Mars… or even currently.