Kit Kat has not been officially announced, although Google has put out an official promo video for the upcoming announcement of Kit Kat. With the new version set in stone, or on Google's lawn rather, you knew that theme developers would begin to release their ideas of what Kit Kat will look like. There is already a pretty sweet looking Kit Kat Concept theme in the play store. It should be noted that this is strictly conceptual since nobody knows what tricks Google has up it's sleeve with this new version of Android in the way of design.
This theme contains 400 themed app icons, and the developer will continue to update this theme with more app icons on a weekly basis. This is a launcher theme and is not a standalone app. The theme works with GO Launcher EX, Nova Launcher, Apex Launcher, ADW Launcher, free ADW Launcher, HD Go launcher, and Launcher Pro. Although this isn't truely a taste of Kit Kat it is nice to see some new unique concepts of what it may look like. Check out this theme at the source link below.
Via Google Play