A reddit user managed to stumble upon a developer unit of the Nokia Lumia 920 that he purchased from eBay. Much to his surprise, however, he found several features not found on the existing version of Windows Phone 8 and something Microsoft may have been saving for later.
The software identifies itself as version 12084.WPMAIN(wpbldlab).20130509-1407, meaning it was compiled on May 9th. An early notification center can be seen in one of the screenshots, providing access to the typical Live Tile notifications. There’s also a redesigned calendar interface with weekly views, and the ability sort applications by name and frequency in the app list. Microsoft appears to be working on multitasking improvements too, with the ability to close apps in the multitasking view.