So I'm playing on the 360 and I go into freeside aproaching the gate to vegas, and I get this powder ganger running at me guns a blazing. The greeter kills him easily and that was his end. Has anyone else encountered a powder ganger in a weird place like this far from their territory? Or is this a scripted event?

Sounds like the assassin guy. And since the powder gangers have faction hostility to pretty much everyone, they got waxed real quick.