User blog comment:JAlbor/Dishonored Interview Opportunity/@comment-94.237.95.194-20120929212034/@comment-5561656-20120930023513

There's three endings with variations built into at least one of them. Two homogenous endings, or rather those that are pure and the third ending would be one with variants built in. I'm inferring that based off of a purely non-lethal ending in which no-one dies and the opposite of that being pure blood-letting. The third ending would most likely be the one with variants built in based on alternating targets that you kill or don't kill. It's possible though that even the two "pure" endings have variations too because of side missions and other factors not presently known.

They've definitely said three endings though and sub-endings or variants in one or all of them.