Interesting idea. Mobiles already can get weather info, but that is reading the data from weather stations whose temperature data may not be the same as where you are, because of local variations. This device will be able to actually measure the local temperature and even may be able to send it to the cloud through an app. Could make for more accurate local weather reports / predictions, if used by many people in the same area.
The article mentions that the device may have some issues.
The method of reading and reporting the temperature is unusual - it uses the audio jack and attenuates the signal according to the temperature, the microphone gets the input and the software calculates the temperature from the variance in the signal (as I understood the post).