Sony (Ericsson) has taken to its mobile Developer World blog to confirm thats 2011 Xperia smartphones, as well as the recently-announced Xperia S and Xperia Ion, fully support the Russian GLONASS positioning service in addition to GPS. GLONASS is run by the Russian Aerospace Defense Forces, and performs similar tasks to GPS, but operates independently of it. By using information from both systems, it's possible to get a more accurate fix of your location in built-up areas where GPS alone may struggle.
Sony says that all its devices equipped with Snadragon S2 and S3 chips fully support both GLONASS and GPS for improved location-tracking accuracy. That means if you have a 2011 Xperia phone, or you're planning on picking up an Xperia S or Ion, you may have an edge over devices which only support GPS. For more technical info, head over to SE's blog post in the source link.
Source: SE Developer World