Apple has yet not revealed the complete specs of brand new iPhone 3G S, still we have come to know about the details thanks to T-mobile website of Netherlands. Though we knew much about the iPhone software update 3.0; specs of iPhone 3G S were still in the dark. Now we know at least something regarding the RAM and processor.
The Dutch site has stated that iPhone 3G S possesses a 600MHz ARM CPU and 256MB of RAM. Just compare these figures to the previous iPhone 3G, and you will come to know that there has been an addition of 200 MHz whereas an upgrade of RAM by doubling the allocated memory. This is indeed a nice improvement.
Due to the enhanced graphics chip, it is quite possible that the future apps become incompatible with former models of iPhone. Currently, iPhone 3G S uses PowerVR SGX GPU Core graphics chip which enables running the most modern OpenGL ES 2.0. This system enhances the speed of graphical apps and provides more detailed images.
Graphics chip of former iPhone 3G is, unfortunately, not compatible with OpenGL ES 2.0. Though the new system will bring better games; those new games will not be compatible with the previous versions of iPhone.