As reflected in Rick Johnson's .plan update, Raven Software has released the version 0.57 patch for the Soldier of Fortune demo. Here's a local copy (with mirrors), and here are the details on the patch from Rick himself (the full list of changes is so long, I'll spare you all from pasting it here):

We've released the patch for the SoF Demo. This patch mainly represents things we felt were important to fix or adjust in the demo, but only if we could easily merge it back into the demo codebase (as the main game has changed considerably). Below represents my crude notes of items we addressed.

Most of these items were QA'd through the low-violence demo release (for the UK), but as a whole, this has not been QA'd. You can still connect to servers running the original version, but you may notice view height discrepencies (such as when you crouch, you're practically eating dirt). This is only a problem if the server has not been patched.