The last unlockable for the "Darkness Falls, Heroes Rise" game has been revealed. It is titled Diablo 3 Wrath and it is a 6 minute video portraying the battle between Angels and Demons in the Diablo universe. The video is done by animation studio Titmouse (strong name) and directed by Peter Chung, who is credited with the direction of The Chronicles of Riddick: Dark Fury, Rugrats, and many other great movies/series.
Note that Diablo 3 Wrath is NOT an ingame cutscene as has no spoilers in it whatsoever.
And for an interview with all the people involved in the creation of Diablo 3 Wrath: