According to The Unofficial Apple Blog:
Apple has updated its US iPhone 4S tech specs page to say that the new devices supports GLONASS positioning systems. GLONASS stand for Global Navigation Satellite System and is the Russian version of GPS that was developed in the 1990s. According to Wikipedia, the GLONASS system fell into disrepair in the 90s as the Russian economy sank, but in the last decade the system has come back with Russia launching its 24th satellite last year, giving GLONASS coverage to every inch of Russian territory.
Before GLONASS, the iPhone only supported assisted GPS. There's no word from Apple yet if the iPhone 4S will take advantage of both systems simultaneously on a world wide basis to give users more accurate positioning data. Also, at this time only the US iPhone 4S page has been updated to note GLONASS support.
http://www.tuaw.com/2011/10/19/apple-confirms-glonass-support-for-iphone-4s/
The iPhone has assisted GPS, and regular Glonass? Does the iPhone support autonomous GPS?
It appears to on my 4. I can put it into airplane mode and the theodolite app still shows an updated position.
Interestiing.
