iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Apple Posts User Guide for iPhone 4 and iOS 4
For those people with a few hours to kill either waiting for a pre-ordered iPhone 4 to arrive or camping out to purchase one tomorrow, Apple has posted the user guide (PDF link) for iPhone 4 and iOS 4 for your reading pleasure. The 243-page guide, which is also available in an iPhone-formatted version accessible through Safari for iPhone, is broken down into 28 chapters and offers information on the features of iOS 4 as they relate to Apple's new iPhone 4 and 3GS devices.
The user guide covers a multitude of topics, from physical features of the iPhone to setup and on through the various software offerings included by default on the devices. Also included are sections on the iTunes Store and App Store, as well as Apple's free iBooks application available separately through the App Store and the iPhone's Nike + iPod capabilities.