Hi all,
If you've just bought a 4K TV or monitor, you're probably looking for things to try on it. I'm happy to report that I managed to get the game running at 60fps at 4K on an Nvidia 970, with some tweaks to the settings. 4K is particularly nice for split-screen multiplayer, as it means each player gets their own 1080p display!
I've posted a guide on the discussion board, detailing a.) how to get the game running in 4K, and b.) which settings will typically improve the framerate at memory- and pixel-hungry high resolutions. You can get it here
There are also some 4K screenshots on imgur. You have to download the images for full 4K resolution. You can find them here.
Happy 4K'ing!