Hey there,
it has been a while since my last project - and i didn't finish it till now. Since i got employed there is only a little time left for projects like these 
Cause it is getting cold here and i don't want to sit in a cold car every morning when driving to work i had the idea for this small project.
Spontaneously i ordered an Siemens TC35i - GSM - Module on ebay for 25€ (~35$) - got it two days later in my hands.
This should be the fastest way to start with some GSM - Development 
It took some time to get it up running but the first step has been completed.
Actually i have set up a serial terminal connected to my PC.
I can make calls and found out how to send and receive SMS.
The Module:
Screenshot (Terminal):
Log (Terminal):
Some helpful Informations on AT-Commands:
http://www.cellular.co.za/at_etsi.htm
http://en.wikibooks.org/wiki/Serial_Programming/Modems_and_AT_Commands
http://www.nobbi.com/atsiem.html
List of useful AT-Commands:
So the next steps will be:
1. Implement a small console on MSP430
2. Build a wrapper for sending commands and interpreting the returned Status-Texts
3. Implement the Heating-Control-"Stack"
4. Implement some Monitoring-Code (Voltage, maybe Current -the TC35i - Module can draw up to 2 Amps under bad conditions, Temperature, ...)
5. Develop the final Scheme - not much - just some sensors and digital relays
For Security-Reasons i will only allow reception of commands from a fixed Phonenumber.