What are the shutter speed and ISO ranges for the iPhone 4S camera?
You can scrape that information off photos on flickr taken with an iPhone 4S:

http://www.flickr.com/cameras/apple/iphone_4s/

Here are a few examples of extremes.  The dark end seems to show a max ISO of 800 and max shutter of 1/15, which several dark photos agreed with, and none of the ten I looked at went further, so here are two examples:

http://www.flickr.com/photos/funinthegym/6328079422/in/photostream/
0.067 sec (1/15)
800

http://www.flickr.com/photos/matthewthecoolguy/6534661585/in/photostream/
0.067 sec (1/15)
800

Looking at very bright photographs, I saw a few claiming very high shutter speeds (1/9259 and 1/2600) but none of them matched the same exif format for the shutter speed field as the rest of the iPhone 4S photos I reviewed, suggesting that these fields were modified in post processing.  The lowest shutter speed I saw that matched the format of the other 4S exif files was 1/1842, and the lowest ISO was 64:

http://www.flickr.com/photos/67660035@N04/7110241863/in/photostream/
0.001 sec (1/1842)
64

http://www.flickr.com/photos/xiahou/6298147263/in/photostream/
0.001 sec (1/1842)
64

This should answer your question for highest and lowest ISO, and highest and lowest shutter speed.  Keep in mind I only sampled a few dozen photos on flickr, it's possible I missed the ends of the ranges.

A random sampling from the "interesting" section, showing the mid range of shutter speed and ISO combinations:

Shutter speed
ISO

0.008 sec (1/122)
64

0.05 sec (1/20)
200

0.008 sec (1/120)
100

0.002 sec (1/550)
64

0.025 sec (1/40)
64

0.002 sec (1/464)
64

0.004 sec (1/242)
64

0.042 sec (1/24)
64

0.059 sec (1/17)
800

0.067 sec (1/15)
640

0.006 sec (1/170)
64

0.067 sec (1/15)
640