Dean Jackson on the WebKit blog:
"The past few years have seen a dramatic improvement in display technology. First it was the upgrade to higher-resolution screens, starting with mobile devices and then desktops and laptops. Web developers had to understand high-DPI and know how to implement page designs that used this extra resolution. The next revolutionary improvement in displays is happening now: better color reproduction. Here I’ll explain what that means, and how you, the Web developer, can detect such displays and provide a better experience for your users."
This writeup is an incredibly great explanation of wide gamut issues with a touch on deep color as well. If you are a developer who uses color in any way, you're going to want to read this. Wide gamut displays are already here.
And of course, Acorn has had support for displaying both wide gamut and deep color images since last fall with the release of OS X 10.11 (I'm pretty sure Acorn was the first 3rd party Mac app to do so).
Do you have a late 2014 iMac (Retina 5K)? Then you've got deep color support. And if you have a late 2015 iMac (Retina 5K) you've got both deep color and wide gamut (via Display P3) support.