Some more info, mainly about AI.
Dishonored, Bethesda's newly-announced action-adventure, positions itself as something different. Led by Thief designer Harvey Smith together with Arkane head Raphael Colantonio and Viktor Antonov (who designed City 17 for Half-Life 2), the new project offers a fairly boilerplate story, featuring regal betrayal and supernatural powers. However, developer Arkane intends to use this setup - you play as a framed bodyguard who's secretly a master of stealth, and even more secretly a talented magician - to make Dishonored more interesting than the standard sneaking-and-neck-breaking fare.
Rather than grouping player abilities into standard healing/damage/manipulation categories, a la Bethesda's own Elder Scrolls series, Arkane equips players with more open-ended powers designed to encourage creative problem-solving. The studio says that enemy AI is strong enough to allow tactics like distracting or overwhelming enemies (remember, giving a computer human fallibility is much harder than just making it really clever) and that environments are interactive enough to figure into complex, player-driven strategies. This in turn feeds into a "chaos" system, which tracks the player's collateral damage and alters the story accordingly.
The games looking really interesting now, and the AI system sounds great.