iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Late Breaking iPhone SDK Rumors: EDGE OK, Apple's Cut, Mac-Only SDK
Of significance, MacScoop says that although applications will have some limitations (iLounge: no access to connected peripherals), iPhone applications will be allowed to use both EDGE and WiFi for data.
The site also confirms suspicions that Apple will be wanting a "small percentage" of revenue from iPhone application sales. The site notes that they were unable to obtain information regarding the specifics of non-commercial (free) application distribution, though Electronista has previously said that Apple would not restrict the distribution of free applications.
Lastly, the site notes that the SDK will require a Mac running Mac OS 10.5 "Leopard," and will be facilitated through an enhanced version of XCode which is to be made available to all Apple Developer Connection members.
The iPhone SDK event starts at 10am Pacific, 1pm Eastern on Thursday, March 6th. MacRumors will be unable to provide live access, but we will post a comprehensive list of live coverage closer to the event. We will provide SMS updates if Twitter cooperates.