The S5L8940 is the Apple A5 processor currently used in the iPad 2 and the iPhone 4S. Manufactured by Samsung, the processor itself is dual-core. The processor (H4P) is clocked at 850MHz in most configurations.
The S5L8940 chipset has a 45nm dual core PowerVR SGX543MP2 GPU which is clocked at 200MHz.
There are no known exploits.