Globally unique texturing is a pretty substantial milestone in game graphics. As Carmack notes in the interview, we've come to accept repeated textures in games because they've been used as a necessary form of compression. Once that constraint goes away, we should see a big step up in perceived visual fidelity. I don't think the effect probably translates well into stills, but you can see screenshots of ET: Quake Wars at the Shack. They have a preview of the game, as well.
Oddly enough, Carmack says the code needed to do the needed virtual texture management and the like is not terribly complex (about a page of pixel shader code) or resource-intensive (it will require newer graphics hardware but isn't especially demanding.) The MegaTexture technique has its limitations, but Carmack says he's now found a way to do unique texturing for all surfaces in a game:
The MegaTexture works for things that are topologically a deformed plain, like an outdoor surface, and it has certain particular limitations on how much you can deform the texture mapping there. For the better part of a year after that initial creation, I have been sort of struggling to find a way to have a similar technology that creates this unique mapping of everything, and use it in a more general sense so that we could have it on architectural models, and arbitrary characters, and things like that.Can't wait to see it.
Finally, I found a solution that lets us do everything that we want in a more general sense, which is what we’re using in our current title that’s under development. That was one of those really happy programmer moments, where I knew that this sense of unique texturing was a really positive step forward for what we could do artistically with the game.