First, we heard that KitKat would bring some changes to the API, breaking many of the SMS apps we've come to rely on. On the day KitKat was released, we were given a more full explanation, shining some light on the technical details and exactly what types of apps would be affected. But did anybody really think this was the end of the story? It turns out that a hidden permission exists which can still grant non-default apps the right to modify the SMS database just like they used to - no rooting required.
The next version of Android is bringing a lot of visual options to the table, and they're not just for Google to play with. Buried deep within the KitKat 4.4 API (level 19) is the ability for apps to request translucent system UI overlays, specifically on the top notification bar and the bottom navigation bar (if your device has one). You can see this feature in action in all the promotional photos of the Nexus 5's homescreen, where the wallpaper is visible form the top of the screen to the bottom.