Starting with zero Arduino experience just a month ago and many forum searches and mis-soldered connection I have made this progress:
the DS18B20 temperature sensor up and running using the OneWire library. (http://www.milesburton.com/?title=Dallas_Temperature_Control_Library). I had some connection problem but that is all worked out now and I get reliable temperature readings. (I realized after I purchased this sensor that I could have got the cheaper and much simpler analog sensor)
data logger shield build and working. logging data to the SD card from the temperature sensor.
16x2 LCD display with SPI interface so I can get the current temperature
have the phone connection working with the voltage divider circuit and can send and receive messages
(it is a fine day!)
I will have to get the Fido code and start to work with that.
Long term I would like to build a small RF temperature / moisture sensor I could deploy through out my farm.
Thanks for the updates with your progress I'm following right along.