Besides the Samsung Galaxy S III, there also has been talk that the Samsung GALAXY Note II would also jump over Android 4.2.2 to Android 4.3. Both models are currently powered by Android 4.1.2. Considering that Android 4.3 is available, it makes sense for Samsung to start pushing it out now to its top-shelf models.
The post from Deutsche Telekom didn't mention a date when we could expect the update to begin rolling out. Just recently Android 4.3 was made available for the Google Nexus 4, Google Nexus 7 and Google Nexus 10. Last week, the new Android build was also sent out OTA to owners of the Google Play Edition of the Samsung Galaxy S4 and the HTC One.
source: AllAboutSamsung (translate) via UnwiredView