iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Apple Now Offering iMacs Equipped With VESA Mount Adapters as $40 Upgrade
The iMac with Built-in VESA Mount Adapter is ready to pair with your favorite VESA-compatible wall mount, desk mount, or articulating arm (sold separately). This iMac doesn't include a stand, so a mount is required. If you don't already have a mount, you can purchase one when you configure your iMac.
Apple is currently quoting shipping estimates of 7-10 business days for VESA-equipped iMacs, compared to immediate availability for standard models.