The DHT11 gives output for temperature and humidity calibrated digital signal.
Every sensor of this model is temperature compensated and calibrated in accurate calibration chamber and the calibration-coefficient is saved in OTP memory.
Stanislav “CW” Simicek did some good work and made a C# class available, see http://forums.netduino.com/index.php?/topic/2560-dht1122-sensor-managed-driver/. This worked fine for me and I’ve used this for the logging.
For a detailed description see also http://embedded-lab.com/blog/?p=4333