Both OpenSprinkler and OSPi support 8 stations, among which one can be assigned as a pump / master station. Moisture sensor is not supported by default but you can modify the software to add support. Both OpenSprinker and OSPi have analog input pins.
For comparisons between OpenSprinkler and OSPi please check the information here:
http://rayshobby.net/?page_id=5816/#faq