Changes are said to include:
?Ongoing fixes and adjustments to the user interface.
?Additional fixes to address audio crackling sound encountered when Dolby Digital is enabled.
?Fixes for Blu-ray software issues that can result in 0×21 or 0x87de07d1 errors.
?Update to address an issue where ejecting a Blu-ray disc after the drive is idle can result in the disc being pulled back in, requiring a second eject command.
?Fix to address Kinect not responding to “yes” or “no” after issuing the “Xbox, turn off” command.
?Updates to reduce or eliminate Blu-ray drive “seeking” sounds after drive is idle (experienced in the 1403 update.)
?*NEW CONTROLLER FIRMWARE UPDATE*
?Update to help address controller disconnect issues.
?Update to help address headset adapter audio quality.
?Fix for LiveTV audio outputting in stereo instead of surround sound.
?Update for the Blu-ray player to fix an issue where it can freeze if left idle or paused for an extended period of time.
?Update to fix an issue where fast forwarding or rewinding an external video source results in screen freezing when surround sound is enabled.
?Fix for video playback stuttering while audio plays back normally in several apps (Netflix, Amazon Instant Video, etc.)
?Game save progress bar will now display when syncing cloud game saves.
?50Hz Blu-ray player support for content recorded at 50Hz.
?Improved GameDVR video quality.
?Online friends notification, including the ability to filter notifications to all friends, favorites only, or disable friends online notifications altogether.
?Requested by the update preview community: Manually install available updates. If a new system update is detected as available, a button will appear under Settings, System that will display “Apply Available System Update.” Note: this feature is being enabled after this current update completes installation. This feature will be available to preview when the next update is made available.
?A new ability to automatically redeem a license code from console messages. For future console messages that include a 5×5 license code, a new option will appear to allow you to automatically redeem the license, versus having to copy and paste the license code.
The list of the latest made it to the private forums on NeoGAF and then was posted here.