Some screenshots showing a pre-release version of Windows Phone OS running on a Lumia 920 have been posted by a Reddit user which could possibly be the Windows Blue update.
It seems that the user who purchased the phone from eBay got a phone running internal Windows Phone build. The build id was 12084.WPMAIN(wpbldlab).20130509-1407 which means it was compiled on 9th May 2013. The screenshots show some interesting improvements which were long demanded by users including the notification center.
The notification center is accessible via a live tile next to the phone tile on the start screen. The calendar app is also redesigned with week view included. The multi-tasking ability also seems to be improved, including ability to close open apps. There is additional button above the app list to sort the apps according to the frequency of use.
The Here Drive has a '+ Blue' at the end, this may indicate that its the 'Blue' update , but it is not clear.The verge's sources have said that this is indeed an early version of Windows Blue.
Via | Source
It seems that the user who purchased the phone from eBay got a phone running internal Windows Phone build. The build id was 12084.WPMAIN(wpbldlab).20130509-1407 which means it was compiled on 9th May 2013. The screenshots show some interesting improvements which were long demanded by users including the notification center.
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The notification center is accessible via a live tile next to the phone tile on the start screen. The calendar app is also redesigned with week view included. The multi-tasking ability also seems to be improved, including ability to close open apps. There is additional button above the app list to sort the apps according to the frequency of use.

The Here Drive has a '+ Blue' at the end, this may indicate that its the 'Blue' update , but it is not clear.The verge's sources have said that this is indeed an early version of Windows Blue.

Via | Source