Ahead of the consumer launch, Windows Phone 8.1 Update has begun rolling out to developers through the Windows Phone Preview Program for Developers.
Phone developers will also receive an updated Windows Phone 8.1 emulator package. The update includes consumer VPN support, Bluetooth connectivity improvements, and Store app live tiles support and Live Folders to help developers get their apps discovered, installed and launched more often.
The update contains no new developer APIs. For more details on Windows Platform Developer August Updates see http://bit.ly/1o6Lm8h