There have been reports that some sensors have pin 3 and 4 reversed, probably as a quality control/manufacturing issue. If you have issues, consider grounding both pins 3 and 4.
I've tried 2 different DHT11's and get the same result
the sensors came from hong kong via eBay
Serial.print("h = "); Serial.println(h); Serial.print("t = "); Serial.println(t);
DHTxx test!Read failh = 0.00t = 0.00Failed to read from DHTh = 0.00t = 0.00Humidity: 0.00 % Temperature: 0.00 *Ch = 0.00t = 0.00