The Retina display has quickly become commonplace on Apple devices. (The term is Apple's parlance for a screen with a high enough pixel density that your eye can't distinguish individual pixels at an average viewing distance.) The iPhone 4, 4S, and 5 each have a Retina display. So do the 5th-generation iPod touch, the high-end version of the 15-inch MacBook Pro, and, of course, the 3rd-generaton iPad. And rumor has it that Apple will unveil a Retina-equipped 13-inch Macbook Pro on October 23 as well.
Unfortunately, the iPad Mini display may be limited to the same 1024 x 768 pixel resolution as the 1st- and 2nd-generation iPads, a move that would certainly make life easier for iOS developers. The 3rd-gen iPad's 2048 x 1536 display has twice the resolution of its predecessors, and uses pixel doubling to maintain capability with lower-res apps.