GPS via GSM Tracking Unit

Update: This is not the best way to track your payload. You will likely waste time and money if you proceed with this approach. While this will work there are better and cheaper options. Please read the newer posts!
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Update on the project:

Finished piecing together the GPS / GSM tracking unit. Used an Arduino Uno R3 Plus. I picked it up at Fry's Electronics (best prices worst customer service). The Arduino is the micro-controller that all the code is loaded on to.

Next, I soldered up the GSM Shield for the Arduino. This allows me to connect the Arduino to the inter-webs using AT&T's 3g network.

Finally, I threw together a simple custom shield I built for the GPS unit. It gathers GPS data from up to 20 satalites. It is built on sirfIII technology. For the GPS module itself I used the PMB-648.

The entire unit works by connecting to the GSM network and then taking the data it recieves from the gps and transmits it to where ever I want.

Not sure yet how we will collect the data. I might transmit data via SMS (text messaging).
I have seen projects where the coordinates are sent to a TCP server running a python script (most likely the option we will choose).

Also, the code for this unit is complete. I want to do a little more testing before I upload it.

Below are a few pictures of the completed tracker! (I still need an antenna for the GSM module....)