Ed - in the video its an LM35 sensor. However this does not go below 0 Centigrade and although you can see the test alarming at a warmer temperature, the real interest is to watch for freezing temperatures. I have the digital humidity/temperature sensor 2302 but the supplied library crashes the compiler at the moment, so that work in progress.
I am waiting for the GSM/GPRS module to arrive in the post, they are cheap as chips from China.
Power management will be essential in the finished version. It will be running on shore power and will alert when it detects a change over from shorepower to battery (i.e power fail). However I am talking to a Microcontroller expert at work about putting the chip to sleep and waking it up on a timer or an external event input (movement sensor?)
There are some libraries which mean the remote Arduino can feed into Google charts so the status can be seen from an Internet web page with the data fed in from the Arduino - I like the gauge chart and can feed temp/humidity to this with an SMS text on reaching an alarm limit -
https://google-developers.appspot.com/c ... lery/gauge