Sprint announced the Optimus F3 this morning, a very boring little phone you probably couldn't care less about, and I don't blame you. What you should care about, though, is what's going on in the official press photos below. Look closely at the one on the left.
Left to right: Optimus F3 IP Infringement Edition, Optimus F3
Why yes, that is a slightly older version of TouchWiz (Nature UX 1.0, if I'm not mistaken) that this Optimus F3 is running!