The Mars Phoenix lander has finished its first "wet chemistry" experiment and has turned in part one of its "lab report." It seems that the pH level and mineral content of this regolith sample are similar to some soils found on Earth - not extreme in any way. Probably compatible with life, though that is not to say that there is or has been life, just that Earth soil with these chemical properties would be able to sustain a lot of living things - from bacteria to certain vegetables.
There is also water there (sublimating ice crystals have been seen in the trenches dug by the Phoenix robot arm), so you can imagine future Mars explorers growing their asparagus in greenhouses using Mars "soil" and Mars water! The image shows a greenhouse on Mars sometime in the future (courtesy NASA).
As usual, Emily Lakdawalla at the Planetary Society Weblog has all the dirt on the Martian dirt. Check out her extensive sol 30 update here.