[stratomorph]

>In tracking the sensors on each of the phones, we observed that the GPS in Nexus S could function up to altitudes of about 60,000 ft. and would actually start working again on the balloon’s descent. ... Maximum Speed: 139 mph

The unit shut itself off passing 600 at low speed, which is more restrictive than required. The rule is receivers that work above 60,000ft and 1000kt require export licenses as munitions (http://www.armscontrol.org/documents/mtcr), but there's no reason a phone's civilian-grade (unrestricted) receiver shouldn't work up high at that low forward speed. I suppose the most conservative possible interpretation keeps companies safe.