Windows Phone Preview for Developers getting Windows Phone 8.1 update
Other problems fixed include the inability of the HTC 8X and HTC 8S to receive the Windows Phone 8.1 update. Those two models did not have the proper drivers installed, which caused Microsoft to stop trying to update the two handsets.
Lastly, more Lumia owners who are members of the Developer Preview program, will start receiving the Lumia Cyan update. Microsoft had started rolling it out for some models a few weeks ago. But the guys and gals in Redmond plan on speeding things up. Every day, a couple of more devices will be receiving the update until all Lumia models are accounted for. The Lumia Cyan update includes a new Start screen, the Swype-styled Word Flex feature, a file manager, IE11 password improvements, calendar enhancements, and an Action Center for notifications.
Those who are members of Windows Phone Preview for Developers get to test out new Windows Phone builds before they are made available to regular Windows Phone members.
source: Microsoft via WPCentral