The newest Famitsu has some information on Metal Gear Solid 4, it states:
- Sunny: A female who has escaped from the grasps of the "Patriots"
- Trevin: An individual involved with weapons-laundering who can erase IDs from weapons so that they can be used again.
- Little Grey: A mysterious creature who accompanies Trevin
- Others: Meril, Jonathon, Ed, Haven Trooper, etc.
More info at the source