I expect the main countermeasure to cellular position tracking will be the use of one-way pagers. Keep your cell phone turned off, and if you get a page when you're someplace you don't want them to know, wait until you leave before you return the page.
The best countermeasure is to reduce its usefulness to law enforcement by reducing its success rate. If there's enough press coverage of the fact that the capability exists, then clueful crooks will not use cell phones. Just like with escrowed crypto, you'll only catch the really DUMB terrorists. All technology aside, the best way to make progress in this area would be if the next James Bond movie shows the capability being used. Then even clueless crooks and drug dealers will do the equivalent of "gosh, well, I saw it on TV!" and will believe the threat. Hmmmm.... Makes me think that a great way to make progress is for cypherpunks to start submitting scripts to hollywood about presidents who get in massive trouble when their personal communications are subpoenaed and crypto keys are de-escrowed to prove that they had sex with office staff.... Nah, that's too stupid... mjr. -- Marcus J. Ranum, CEO, Network Flight Recorder, Inc. work - http://www.nfr.net home - http://www.clark.net/pub/mjr