"Dark Souls: Prepare to Die Edition includes new bosses like Artorias of Abyss and Chimera of Tomb plus brand new weapons and armor. Pick up Dark Souls for PC and all of the extra content is included in with the game.
If you already own Dark Souls for PlayStation 3 or Xbox 360, you can grab the Artorias of the Abyss episode online as downloadable content. Dark Souls: Prepare to Die Edition is slated for release on August 24."
Also a new trailer as well but I don't have a Youtube account, nor feel like spending the time to make one to link it.
Pretty damn awesome though. I certainly will be picking this up.