The iPhone 4S receives a total Geekbench score of ~622. This falls slightly below the iPad 2 scores of 749, but well above the iPhone 4 benchmarks of 370. So, the new iPhone seems to benchmark about 68% faster than the iPhone 4, and about 17% slower than the iPad 2.
The iPhone 4S A5 processor is likely underclocked (800MHz) as compared to the iPad 2 processor (1 GHz), explaining the slightly lower performance.
The iPhone 4S is currently shipping to customers for delivery on October 14th, but it seems at least a few units are already in the wild.
Update: Anandtech compiles these results (and more) in nice graphs:
Meanwhile, graphics performance of the iPhone 4S is confirmed to be about 7x faster than the iPhone 4.
Read more http://www.macrumors.com/2011/10/11/iphone-4s-geekbench-benchmarks-68-faster-than-iphone-4/