I just wanted to share with y'all that I'm uploading a superfast speedrun as we speak, about 37 minutes (not the quickest though, because I exclude some minor stuff). I show how to do each of the 9 main missions (target-and-back) the fastest and with low chaos at the end. I did Kingsparrow Island in just over 3 minutes, for instance.

Prison & Sewers - 4:53 (improved version after feedback from smashly below):
http://youtu.be/jNOmFh1rIsA

Feel free to check out the rest of the playlist (w/ commentary):
@ http://www.youtube.com/playlist?list=PL0A042B3D1E37BDDD&feature=view_all

Note: The reason I don't add the Dunwall Tower intro, Blink tutorial or Weepers tutorial to the videos is because they're too short and linear to really add anything extra to the speedrun. You're gonna do those missions pretty much the same way, whether you speedrun or not. Also, the second mission is necessarily the longest in the game, because the 2 extra runes from Granny Rags allow you to upgrade Agility and Blink 2 much earlier, saving you a little time.

Hi,
Thanks for sharing you efforts.
You could speed that run even more since your allowing for occasional kill.

First 3 guards, knock out the first one while the other 2 are talking.

Don't hesitate at the control room, just keep going onto pipes.
When you get to the last 2 guards ignore them, head along the pipes on the right, drop down plant bomb and duck off in to container on left.

In sewer when you get to the Crank Wheel with the rats.
Don't wait and feed bodies, leg over the top of the rats and jump on the back of the Crank Wheel and start cranking.
You'll be leaving and the rats still haven't finished munching the body in front of the crank wheel.

Almost shave 1 min off just doing those 3 things.

Paraphrasing:

Thanks alot for this advice, I'm uploading an improved video now. I manage to actually shave off more than 1 minute, even. Thanks again.

Good to see man.

I got another tweak for your Mission 9 speed run.
No Crouch, No Wait, No Kills and Not Seen: 2:30 min
http://youtu.be/SKRbxhBjsNg
(sorry about the low qual vid, I just don't have the bandwidth for decent quality vid uploads)

So it looks like you'd only shave 30 ~ 40 secs.
After I made my own attempt I saw another vid of someone else who gets it 2:05 min

Edit: just watched another vid of someone doing it in 1:32 min, now that's like lightning...swoosh
Crazy all the different paths ppl take.