According to this unsourced report, the Belarusian mobile operators have cooperated with the country's secret police to provide a list of everyone who was in the vicinity of an anti-government demonstration; the spooks are now calling in everyone on the list to interview them about their involvement in political dissidence. I'd love to see a better-sourced version of this article, but it's technically possible for the operators to have logged every phone near a given tower at a given time.

This is one area where I really agree with Evgeny Morozov, who has written extensively about the risks that technology use poses to demonstrators: at present, mobile phones are not fit for purpose. Mobiles are too closed, the mobile operators too vulnerable to be considered safe enough for use against powerful hostile states. Unless your mobile-driven protest ends with the collapse of the state, it's all too likely that you and your friends will face dire reprisals.

It's one of the reasons I'm so anxious to see more free/open phone operating systems, which open up possibilities for IMEI spoofing, anonymizing tunnels through proxies, etc. But until there's widespread adoption of open handsets, your phone is eminently capable of finking you out.

Mobile operators rat out all demonstrators

(Thanks, Svabodu!)