Raven's Rick Johnson updated his .plan with a status report on the Soldier of Fortune demo, which he now says to expect Monday:

SoF Demo News

The Demo will be officially released Monday. It got delayed until then mainly because QA found another crash bug Thursday (in the same function, ironically, but different area). Friday, I decided I wanted to try and address a 3dfx driver related bug. On certain drivers (kinda a mix of processor and OS), texturing would completely screw up. I changed the code so that on 3dfx, the game would not enable a specific rendering feature. This took a bit to QA today (to track down a related problem that got by me). I just got done talking to Mike Denny, who is in charge of QA for SoF. We have their blessing to release the demo (finally)... But because of "outside influences" it was decided to hold up until Monday.

Just to give you a brief rundown of the Demo features:
4 single player maps (a tutorial level, 2 full playable levels, plus a cinematic level)
2 deathmatch maps
12 different deathmatch models / skins representing 3 teams
In game server browsing
and a ton of custom options (including custom game settings (such as disabling spawning))

The demo will weigh in at a hefty 95 megs, but should fit on zip disk.