id Tech 5 is going to introduce the entire concept of megatexturing - the grand unifying theory of geometry, just as Doom 3 was the first major engine to implement a unified lighting model. This is going to have major implications for both content production and rendering, and is exciting as fuck.
Carmack's impressiveness is not only in his ability to write kickass looking engines, but also his ability to lead the pack in completely rethinking the sort of things most devs take for granted.
He uses the name "Sparse Virtual Textures" instead of megatextures so it's not very googleable. Also it's a video, not a paper, but the code is included.