Via blogdex, an interesting newspaper article about the importance of dirt on Mars in scenarios for a manned mission to Mars. A ship carrying humans has to touch down a bit more elegantly than the rovers needed to, and so the landing device has to be designed with the surface conditions in mind. Moreover, given the long trip, astronauts would probably want to stay a while and have to dig out a shelter. Finally, dust control would be a big issue for any electronics (for example the rovers lost energy because of dust on their solar panels ).
The specific example in the newspaper article discusses camping out on soil overlaying an ice bed. Heat from the astronaut's activities might melt out a sinkhole. This is worth thinking about, because "rotten" subsurface ice is exactly where you'd expect microbial life, so you'd want astronauts right on top of it. Check out this Workshop for this spring's Mars fashions.
Maybe a robot or two first.
There's quite a lot more information in the Geology thread of Martian Soil. Also some links are available here.