Sprint owners of the Samsung Galaxy S3 will finally get a taste of the sugary sweetness offered in Android 4.4 KitKat. The update has started rolling out OTA to users. As usual, it will push out in batches, so it might take a while to get around to you so be patient. This update is software version L710VPUCND8.
While it is unsure whether the venerable Galaxy S3 will actually get the update Internationally, it is a good bet that it will roll out to all the carriers eventually. Here's Sprint's news release below.
Source: Sprint