iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
More New iPhone OS 4 Features: File Sharing, App Closing
Currently available with iPhone OS 3.2 on the iPad, iPhone OS 4 seems set to bring this feature to the iPhone and iPod touch, allowing users to drag-and-drop files between certain applications and their computers.
In earlier beta versions of iPhone OS 4, users wishing to close applications in the multitasking tray had to touch and hold each application's icon until an extra "close" icon appeared in the upper left corner of the application's icon and then touch it to close out the application. The awkward and time-consuming process when trying to close multiple applications was a complaint of some users, and Apple has addressed the issue by now allowing users to simply touch and hold one application's icon to activate the close option for all visible applications in the multitasking tray. Once activated, users can quickly close multiple applications.