The screencapture above shows four devices running various versions Windows Phone 8.1 caught by Love Wallpaper HD's server. Their OS sub-version numbers range from 12073 to 12102, however there's no mistaking what "8.10" means. XDeviceEmulator from Microsoft is obviously not a real device. Nokia P4301 is one interesting item though. According to the server log, the phone has TWO different resolutions: 800 x 480, and 1280 x 768. This could mean either the device's resolution is somehow adaptable, or "P4301" actually means an array of testing devices inside Nokia.
Anyway, it's great to see Windows Phone 8.1 being tested. If the OS update is already in a functioning shape, the final release can't be too far away--though rumors of a late 2013, early 2014 may still hold true. With a bit luck, maybe the majority of existing Windows Phone 8 devices could get it before the New Year's Day?