There has been a lot of information coming out about what Windows 8.1
(Blue) will add to Windows 8 or Windows RT devices, but there has been almost no mention of what the update will do for Windows Phone. A new leak suggests that Windows Phone Blue may be in line to get VPN, Bluetooth 4.0 and LE support.
The leak is actually based on features that are coming to Windows RT with Blue, and those features are expected to filter down to Windows Phone, mostly because Microsoft had posted a job back in February looking for someone "to bring much of the WinRT API surface and the .NET Windows Store profile to the Phone."
Justin Angel, former employee of both Nokia and Microsoft, has been combing through the Windows Blue image for RT and he's found support for VPN, Bluetooth 4.0 and LE, as well as support for Low Lag Camera APIs, which helps with HDR image capture. There are also references in the image to geofencing (which Google just added to the Maps APIs), options for apps to edit music playlists, and wireless streaming similar to AirPlay.