The HDMI specification has been updated to 2.0. From versions 1.3 and 1.4 which were released around 7 and 4 years ago, the standard has now been updated to include support for larger resolutions such as the emerging 3840x2160p60.
The improvements as you can probably guess are mainly focused at adding the ability for 4Kp60 content to be carried across the cables as whilst previous specifications had handled this resolution they were at lower refresh rates.
This allows for greater than High Definition content to be played smoothly on TV's that support it (which is not many at the moment). The main reason for this increase is down to the improved overall bandwidth of the specification to 18Gbps from 10.2Gbps and lower in previous versions.
Other improvements are:
4K@50/60, (2160p), which is 4 times the clarity of 1080p/60 video resolution
Up to 32 audio channels for a multi-dimensional immersive audio experience
Up to 1536kHz audio sample frequency for the highest audio fidelity
Simultaneous delivery of dual video streams to multiple users on the same screen
Simultaneous delivery of multi-stream audio to multiple users (up to 4)
Support for the wide angle theatrical 21:9 video aspect ratio
Dynamic synchronization of video and audio streams
CEC extensions provides expanded command and control of consumer electronics devices through a single control point
Thankfully the new specification is does not mean new cables, with the 2.0 specification not making any changes to the current HDMI connectors.