I recently received a new AM2302 temperature / humidity sensor. It's a fully-assembled, wired, version of the DHT22. It seems to be almost too simple to implement. There are 4 wires: one for 5v power (connected to a built-in resistor), one for data and one for ground. There's a fourth wire, in between the 2nd and 4th, which is supposedly useless. But I've heard that it works better if that is also plugged in to ground.
I found the DHT library and example code, copied and pasted a few routines in to my basic code. I plugged the 4 wires in to my mini breadboard and then to my Arduino Uno.
In less than a half an hour I had a fully operational temperature / humidity display program running (hardware & software).
It just seems too easy. I must be missing something. I am counting on you experienced Arduino engineers to tell me what I have forgotten or not adjusted for.
My whole project is here:http://fritzing.org/projects/arduino-am2302-on-a-mini-breadboard/