We dont need to know how GSM is transmitted, or what encryption schemes they're using. If you are outputting a signal, you can be found. Hell, there's competitions for RDF.
Now, just not carrying a cell phone is a good idea on not being tracked. Next best is taking the battery out of the phone. "Off" does not mean off, even in airplane mode. Some GSM frames are still transmitted, as per what my fellow ham geeks have told me (I'm one as well).
Other than the government decoding your GSM communications (which it can just ask Ma Bell to tap without a warrant and get away with, according to the W.Bush-era abuses) I don't see that particular un-free code helping in tracking or spying on you.
http://news.cnet.com/2100-1029_3-6140191.html
Tin foil hats wouldn't be quite as silly if mind control rays were real and already used in the field.
ESR stated in Revolution OS that RMS's 'wholesale attack' on (was it software patents or intellectual property? i don't remember now) was one of the reasons it was hard to convince businesses this wasn't just a hippie pipe dream.
The OpenMoko runs all Free code, afaik, so the whole "being tracked by Big Brother" deal sounds like tinfoil hat syndrome. This particular rant only points out that most cellphones run on proprietary software. Why don't we just shout about anything that uses proprietary software like cars or industrial manufacturing equipment? We know it's proprietary, but comparing it all to a fascist regime isn't going to contribute positively to a discussion to make it more open.