The game will be a sequel to 2002's Soldier of Fortune: Double Helix and will run with the subtitle, Payback. The game will be a sequel to 2002's Soldier of Fortune: Double Helix and will run with the subtitle, Payback. Adults only Ranking.

Activision confirmed the rumours with a short and simple quote for Kotaku, saying; "Soldier of Fortune: Pay Back is being published by Activision's Minneapolis office [Publisher: Activision Value]. We have no further information to share at this point, but hope to very soon."

Update
According to a source which wishes to remain anonymous, the slowakian developer of the new Soldier of Fortune game is Cauldron who created the History Channel: Civil War FPS for Activision Value in 2006. Other games from Cauldron: Civil War, Gene Troopers, Knights of the Temple 2 and Chaser.

Activision Value is a budget priced game brand.

Source :: shacknews
first four Pictures :: Gamestar
first little Ingame Footage Video :: dailymotion

I read the game will be released in autum 2007/21. November for PC, Playstation 3 and Xbox 360 in the Activision-Value-Series so that this game will not be a fullprice game.
So it will be graphically a next-gen game, whatever that means, for low price. We will hear and see more on the E3 exibition.
Raven Software, Developer of the last two games is not involved in the new game. The new Engine is so far not known, somebody said it runs on the Q3-Engine - i doubt it.

The SOF Series is known as über-brutal FPS.
Both titles are still currently played online, in the game modes DM and CTF. SOF 2 needs the goldpatch (look at SOFFILES).
I described myself as a 5-minute player the skill as "shoot at the right moment or you lose" like FEAR.

To get an impression of the older titles watch game-movies from own-age (Soldier Of Fortune 2 FragHighlights). I watched some few good movies in the past, but my brain delivers me no titles anymore. Sorry for that :)