The Galaxy Note 3 has already been getting its fair share of KitKat, but now it's the Galaxy S4's turn. The Exynos 5 Octa version of the international Galaxy S4 is getting Android 4.4.2 via an OTA update. If you have a GT-i9500, don't go checking for updates just yet – this rollout is starting in Russia.
This update (version I9500XXUFNB3) brings all the usual KitKat goodies including a camera shortcut on the lock screen, default SMS settings, music album art on the lock screen, some keyboard improvements, UI tweaks, and white KitKat-style status bar icons. It's a 1.5GB download and there are links below where you can get the OTA file to flash manually, but do so at your own risk.
It should be noted that this update is only for the Exynos device. There is also an international Snapdragon version of the GS4, the GT-i9505. That one is still waiting, but a few US Snapdragon variants on Sprint and US Cellular have gotten surprisingly fast KitKat OTAs.