Nena Mark 2 site just benchmarked the Verizon version of Samsung Galaxy S4. The model no is SCH-i545 which is similar to model no of Samsung Galaxy S3. According to NenaMark 2, the screen has resolution of 1080X 1920 and is powered by 1.9GHz processor. The phone would run on Android 4.2.
Earlier it was rumored that the latest phone from Samsung would have PowerVR GPU but as per NenaMark2 site, Samsung Galaxy S4 would be powered by Adreno 320 GPU which would make it a real powerful device against Sony Xperia Z and Apple iPhone 5S.
The latest date for the launch of the phone is March 15th.