GLONASS stands for Globalnaya Navigazionnaya Sputnikovaya Sistema (or “Global Navigation Satellite System” when translated from Russian) and is Russia’s alternative to the United States’ Global Positioning System (GPS). Its network comprises of 24 satellites that achieved full global coverage as recently as the beginning of this month.
GPS has a little more accuracy than GLONASS in most parts of the globe but the latter provides better mapping of the northern areas of our planet. When the two are combined, the accuracy shoots up by a significant amount and location determination becomes much faster due to the 55 satellites involved (with GPS bringing in 31 and GLONASS 24).
It remains unclear exactly how GLONASS will improve upon the iPhone’s current location features but it will hopefully work hand-in-hand with GPS to fetch your location data more accurately and/or faster.