Currently in Beta, several versions are available for testing on the following link,

http://www.fallout3nexus.com/downloads/file.php?id=14856

DESCRIPTION
Hidden Wasteland Encampment, a mod adding the U.S. Marines into Fallout 3. Located outside of Republic of Dave within a hidden cave. Final release will contain a detailed story driven quest revealing the background behind the settlement and those who inhabit it.

KEY FEATURES
/|\ New world
/|\ New faction
/|\ Custom voiced NPC's
/|\ New items
/|\ Detailed story and quest

PROJECT STATUS
/|\ BETA

REQUIRMENTS
/|\ None, runs on standard Fallout 3

INSTALLATION
/|\ Download latest main file, unpack into Fallout3/Data folder and overwrite any existing files.

Semper Fi.

Keep on it. This looks pretty cool.

Can't wait to kill them.