Just signed in on my Xbox, started up Skyrim and I received title update 1.6, here is a list of new features and all of the bug fixes that have been addressed in this latest TU

1.6 Update (all platforms unless specified)

NEW FEATURES

Mounted Combat - Skyrim now allows you to do melee and ranged combat while riding a horse

BUG FIXES

General stability and memory optimizations
General AI pathfinding optimizations and bug fixes
Optimizations and crash fixes for data leaks
Fixed rare crash with lighting
Fixed crashes related to loading and saving games
Fixed crash with summoned creatures/NPCs
Fixed rare issue where saves would be corrupted
Improved logic for when ranged kill cams are played
Fixed issue with ranged kill cams while killing a dragon
Fixed rare issue with certain ranged kill cams not playing properly
Fixed issue with nirnroot lighting not properly cleaning up
Fixed issue where bow damage was being calculated incorrectly
Fixed rare problem with werewolf kill moves would not finish animating properly
In The Break of Dawn fixed rare issue where Meridias Beacon would disappear from players inventory
Fixed occasional issue where followers would disappear after player pays off a bounty after committing a crime
Fixed issue where certain creatures and NPCs would fail to respawn properly
Fixed rare issue with dialogue subtitles not displaying properly
Fixed issue with water appearing blurry when loading a saved game after creating a save underwater
Fixed issue where map cursor would occasionally disappear after closing a message box with Kinect enabled (Xbox 360)
Fixed rare issue with shouts only performing the first level and not other unlocked levels with Kinect enabled (Xbox 360)
Fixed issue where the shout buttons would stop working properly if users mashed LB and RB during cooldown with Kinect enabled (Xbox 360)

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EDIT: I can confirm it is 1.6 because I am currently riding around on horseback wielding a sword

Edit 2: It also adds a new option of 'Add-Ons' at the load up screen, this will allow you to download the Dawnguard DLC from there when it is released.