The French magazine Canard PC has previewed Fallout: New Vegas. No Mutants Allowed provides a summary of the preview, which is a pretty interesting read.
He asked you to get rid of "invisible monsters" living in the basements. These are a group of NightKins. The journalist's character was pretty weak in combat (Strengh 3, low Gun skill). Moreover, he played on harcore mode, and the combats were rather tough. He was killed quickly by the leader of the Mutants. Then, he tried another way to deal with them : he sneaked and managed to reach their leader... who was friendly ! You could talk to him. The NightKin leader was quite insane : he talked to a buffalo skull which he workshipped as a god. Thanks to his high speech skill, the journalist managed to find a compromise : these Stealth-Boy addicted Nightkin believe the a pre-war shipment of their precious drug was to be find in the higher levels of the site.
The only problem is that the shipment is guarded by a ghoul sniper... who was friendly as well ! He would give info to the player if the later accepted to find a lady ghoul (he wanted to have sex with her... urgh !) who was trapped in the basement when the NightKin came. With little investigation, it came out that the poor lady ghoul was lying dead in a basement's room, attached by the NightKin.