One of the glaring features missing from the Windows Phone platform is a unified notification center. It necessitates having a tile on your homescreen for every single application that you may get a notification from just in case one comes through. Windows Phone 8.1 is on the way as part of Microsoft’s Windows Blue program and as a part of the update it looks like the platform will be updated with a notifications tile to bring the much needed feature to the platform.
The feature seems to be a part of a Windows Phone 8.1 build that was leaked on the Polish site windows-phone.pl and seems to be similar to a feature found on a Windows Phone that was reportedly lost by a Microsoft employee in June which had an early build of Windows Phone on it.
Personally I think that the UI of Windows Phone would allow for a notification center to be built as a swipe in the opposite direction as the one used to get to the full apps list although I think I would accept the total UI overhaul suggested by Christian Del Rosario in his video (below).
Source: The Verge