An API is a specification of the dialect that computer programs or their components use to exchange data with each other or with the hardware they are running on.
The nano does not yet support Bluetooth 4.0 (or any version of the specification), but the standard has been seen as a key component in helping reduce power consumption for such a product, There are also lower power display technologies -- such as Sharp's Memory in Pixel LCD on the forthcoming Meta Watch -- from which Apple has abstained.
Apple has topped them all, and the other manufacturers are going to have to start offering higher specs in storage or run the risk of being left behind in what is the next step in a specification war.
While the DVI standard limits TMDS clock rates up to 165MHz, the HDMI 1.4 specification allows TMDS clock rates up to 297MHz, enabling the support of 1080p 3D at 60Hz, or Ultra HD (4K x 2K) up to 30Hz frame rate.