“The Galaxy S4 is rumored to sport a 4.99-inch Full HD AMOLED touchscreen display, an eight-core Exynos 5 Octa processor, 2GB of RAM, 13-megapixel camera and Jelly Bean right out of the box. However, these specs are not confirmed at this time either.”
Note that the leaked photo has a date of April 22, which hints that the S4 might be publicly released on that date. With previous releases of Samsung handsets, the date had been Photoshopped into the publicity photo.
One more note on this topic: the S4 may be different from the S3 and previous Samsung phones in terms of operating system. The current Galaxy line is built on Google’s Android OS, a Linux derivative, but with apps coded in Java. The S4 might be built on Tizen, another Linux derivative, but with apps coded in HTML5. The goals of moving to Tizen are to increase interoperability across hardware platforms, increase competitiveness of Samsung hardware against Motorola (which was purchased by Google), avoid potential patent fights, and possibly reduce fees paid to other companies such as Google.