This was by far my favorite weapon in Fallout 3 (more specifically the "Fisto!") and anyone who has gotten a critical hit killing blow with one in VATS understands why.  I'll be honest here, if it isn't in the game, I don't think I'm going to be getting it.

It's in the game and a few other variations on it.

Okay, sweet!  Since it requires no ammo, that's my hardcore mode weapon.

" @Shadow:  Fisto isn't confirmed, but powerfists are! "

That depends on what "power of fist" you're looking for.

Yes.  I found a traveling merchant selling one (generic powerfist), but I picked up a sweet bladed gauntlet instead -- more dps :)