There are 8 companions and players will be able to have one humanoid and one non-humanoid companion at any one time. New Vegas also includes an updated interface for interacting with these NPCs. You can read our preview of the game from QuakeCon for more information.
We aren't going to present the full list here as it does contain some potential spoilers. That being said, if you'd like to see who and what you'll be teaming up with, head over to the PlayStation Blog. Just be sure to come back here and discuss what you find.
The comments may contain spoilers. Read at your own discretion.