Marco Arment:

To bring Retina to the 27” iMac and 27” Thunderbolt Display, Apple doesn’t need to wait until 5120×2880 panels are available. They can launch them at the next-lowest common resolution and use software scaling to let people simulate it if they want, or display things slightly larger at perfect native resolution.

That next resolution down, of course, is 4K.

A great explanation of how Apple can do “Retina” desktop displays soon — perhaps very soon — which makes sense to me.

I’m hoping this is sooner rather than later, I have a Retina MacBook Pro and hooking it up to use my 27” iMac as an external monitor is pretty good, but I find that I still edit photos and read lots of text on the built-in display leaving the 27” display empty.