One of the Fb user commented in the Samsung Lebanon Official Facebook page and ask a question about the Samsung Galaxy S IV. After an hour the Samsung Lebanon answered that the Galaxy IV won't be release before May 2013. But it is not 100% confirmed.
Samsung Galaxy S III released last May 2012 and same also with S II, maybe S IV will out same with S III and S IIin May 2013. The Samsung Galaxy S IV feature rumored a Exynos 5450 CPU 2 GHz, Mali-T658 8 core GPU, 4.99-inch SuperAMOLED Full HD, 2gb Ram, a 13 MP rear auto-fucosCamera, 2 MP front camera and run Android 4.2.1 Jelly Bean (some say it will run Key Lime Pie 5.0 OS) So many rumored out but still no one confirmed.