http://www.dishonored.com/ "Dystopian Steampunk Bloodbath" - Forbes.com <iframe width="853" height="480" src="http://www.youtube.com/embed/E1HlYTukh9A" frameborder="0" allowfullscreen></iframe>
It's just a debut trailer, but I wouldn't worry too much about gameplay. It's being developed by some of the same people who made Thief: Deadly Shadows and Deus Ex. Sounds promising to me.
Actually, I think the only link to those games is Harvey Smith, who is co-lead designer of the game I believe. And actually, he didn't even work on Thief (that somehow got misreported). He has an OK record, although some duds too (he had similar control in Deus Ex Invisible War and Blacksite Area 51 as he will in Dishonored I think, unlike his positions in games like Deux Ex 1 and System Shock). Not that I think this means the game will be bad or anything. Arkane Studios has done some interesting stuff, the concept seems good, and hopefully Bethesda backs it well (though I've not been very impressed by their history in games not developed in-house). I'm looking forward to seeing more. That's intentional I believe. Here's a video from a little while back, providing more details and a bit more gameplay: <iframe width="560" height="315" src="http://www.youtube.com/embed/Zze1wpwVl7c" frameborder="0" allowfullscreen></iframe>
Well, they helped make it. 2K Marin was the primary developer for BioShock 2 (and of course, they based their work on what Irrational did). Though seems like Arkane did a lot of stuff like level design and art, so they would still be very familiar with making something like it. Yes, I like to nitpick.