Sensible piece about US State Department funding for mobile anonymity projects, and some interesting stuff. The crack about looking with disfavour on the drowning man and then encumbering him with help once he reaches ground is relevant.
The real prize (as alluded to here) would be a mesh network application that works either instead of the PLMN or alongside it. The only way to avoid leaving traces in the enormous billing/rating/charging infrastructure of your average cellular network is not to use it. According to Comptel, the Finnish OSS/BSS software house, operators spend about €32bn a year on software, of which €11.5bn is in the revenue management segment, another €5.5bn in business analytics, and another €4bn in CRM - €21bn worth of data-mangling kit that could theoretically be repurposed. It's probably better to just leave a GPRS datacall than a phone call to the person you want to speak to in there, though.
On the other hand, there's an API for the US Army.