It’s worth noting that the srcset attribute for the img element has landed in Chromium (Chrome will get it in 34, Opera 21). Their example: <img alt="A rad wolf." src="pic1x.jpg" srcset="pic1x.jpg 1x, pic2x.jpg 2x, pic4x.jpg 4x"> And:
Stay tuned for the <picture> element
We needed this. The fight was arduous. The solution is good. Other browsers will be on the way. This is notable as once a browser supports something, the tendency is for it to always be supported. Plus now polyfills can be true polyfills.