iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Apple Seeds New iPhone OS 2.0 Beta (5A240d), SDK Update (Beta 3)
The updated iPhone beta firmware, version 5A240d, includes a number of fixes and new features centered on Exchange support, including the additional abilities of receiving and accepting meeting invitations, searching for contacts in the global address list, auto-complete email addresses in the global address list, and setting up an exchange account using Autodiscovery (Exchange 2007).
The final version of the firmware is expected in June as a free update for iPhone users and for a small fee for iPod Touch users.
Today's iPhone OS beta replaces the build originally seeded to developers, which incidentally had timed out today.