You had to be waiting for this one, the official Microsoft update and Nokia throws in their added features to complement it. We have seen it in the past with updates like Lumia Amber and Lumia Black.
Windows Phone 8.1 will come with all the features we have been hearing about for the last month: Action center, swipe keyboard, and of course the woman of the hour, Cortana.
Nokia Cyan is supposed to come centered around the imaging side of the operating system. They will focus on Nokia apps like Creative Studio and Storyteller. We will more than likely hear more news as the update gets closer and closer to release, so stay tuned.