Link to Mars Express vulcanism storyNew estimates suggest volcanoes could have been active between one million years ago and 20 million years ago, but more work is needed to refine the dates
Previous spacecraft data suggested that volcanism on Mars ceased some time around 600-500 million years ago.
If volcanoes were active as recently as 1 million years ago it becomes more likely that Mars still has some tectonic activity. Activity that could have released the methane mentioned in prior postings as possible indications of life. On the other hand vulcanism releases material like water and provides heat sources both of which could help any life that is there to survive and prosper.