Apple announced a new interesting desktop that actually has more pixels than its laptops making Apple desktop screens interesting again for some reason other than physical screen size. Apple has also been ahead of the curve on stopping the madness on too many pixels on its phone cameras.
While I think 4K TVs are a bridge too far and 1080p (or in the compatible terminology with 4K, a 1080p screen is 1920 wide is a "2K" screen) is plenty for movies and games, 4K is interesting for uses involving text and hi-res still images. As one experiences in Photoshop on most images, you need to either not see all the pixels by "fitting on screen" or zoom in and see "actual pixels". But for images from any iPhone, we just saw this crossover:
iMac Retina screen: 5120 x 2880
iPhone 4s/5/6 camera: 3264 x 2448
So you can (barely) get the whole camera image on there with "actual pixels". I expect this computer will be very popular with designers/artists/photographers.
Another interesting tidbit is similar to trends in phones, the screens are getting skinnier. While the camera sensor is 4x3 (like ever computer screen I had in the 80s and 90s), the monitor is 16x9 just like most phones these days.