Prior to Dragonborn's release, one of the files found in the patch mentioned something about ripping out someone's heart. Is that still in the DLC and when does it happen? there was some speculation that it was a new kill move. Speaking of which, there were some new kill moves referenced as well, are they in too?

It's during one of the quests you get from the Telvanni Mage, it is not a new killcam sadly.

It is a kill move. It's part of Neloth's quest chain.

It is the final quest you do for neloth before you become a member of the telvanni. you go fight his witch arch- nemesis and after you knock her down you click '' rip heart out'' but its just a heartstone.

Anyone tried pickpocketting a briarheart to see if we get the same animation?

Ah yes! If anyone tries this, make sure to also try it by getting the briarheart on his knees in the "death stance". That's how it was done in the quest.