Noclip just released a documentary about Arkane a few hours ago: https://www.youtube.com/watch?v=h4kdqwdbZZ8. Not much new info on Dishonored itself but pretty interesting nevertheless. You can clearly see the influence their previous games have on Dishonored. Thought you guys might want to watch it.
Edit: I want to add the they will also have a documentary dedicated to Dishonored, which is going to be released around June, July.