Sibrand Isn't Paranoid Enough (Early Death)
http://www.youtube.com/watch?v=3Tww7kpXiA8
[Front paged. - stabguy]
An early death on Sibrand, made possible by glitching out of the city and restarting the mission. For those not familiar with this exploit watch the original video.
http://www.youtube.com/watch?v=MKrs0HyY7hg
Early Death
Since the game knows you started the assassination mission Sibrand is already on ship before you start the cutscene. Getting to him is another matter entirely since he appears back at the scene location if you enter the shipyard directly. So enter it from the south wall by the way shown in the video. There are some guards along the way that can easily detect you, so be careful (or fight them all off like I did). Before you reach the ship Sibrand gets on the docks nearby. He seems to just walk back and forth along it. Killing him results in the memory corridor scene.
Setup
Getting out of the city after the assassination is trickier in Acre than in Jerusalem since Acre has two closed gates at the entrance. So I used a different method. I did the save citizen mission outside of Acre and gentle pushed the citizen all the way to the bureau, then started the mission. Then I moved the citizen all the way to the cutscene and afterward to the target. After assassinating Sibrand I talked to the saved citizen, which resulted in saving the game. Then I desynchronized. When I respawned it was outside of Acre. Saving the game by a talking to a save citizen results in spawning where the save citizen mission started.
Maybe you can do like a corner boost through the gate, or something?
The setup only took about an hour. 
Now we just need a way to exit Damascus. One more thing to mention, last time I was on I entered the shipyard in the way shown in the video (without previously exiting the city). Sibrand wasn't there. After preassassinating the guards there I went to the shipyard entrance. When I came back Sibrand was there and the scene started. Some of the guards weren't there for the scene, including the one handing the helmet to Sibrand and one of the two that threw the dead monk in the water.
So it seems the game doesn't spawn Sibrand until you enter the shipyard normally. I'm guessing the glitch that one player experienced happened because the game spawned Sibrand before he entered the shipyard. As a result Sibrand wasn't effected by the scene that was ready to start and walked away.
Wow, must've taken a long, long time! Great video.