Dark Messiah - Patch News & Tweak Guide (Updated)

VoodooExtreme has a short note from Arkane's Raphael Colantonio on the fixes they are working on for Dark Messiah:

We're currently fixing a lot of the stuttering that happens with Dark Messiah on some hardware: We're modifying the way we're accessing some of the audio and precache files. A patch will soon be released for both the Retail and the Steam version. It fixes a lot of issues, including a few scripting bugs and some performance [issues]. We are really sorry for the problems some of you have had with the game, and be sure we're fixing them all.

...and they are also pointing out a tweak guide at TweakGuides.

Update: this thread on the official forums includes a detailed list of planned fixes and further updates will be posted in that same thread.  This is primarily a multiplayer update.