I was thinking that all the game's companions should have a place to go chill out in whatever wasteland you fire them in. Also, when you make that first crossing into the Mojave it might make sense if your CW companions leave you for dead and get spread out across the place, to be picked up as you find them.
Anyways, some suggestions.
FO3 followers in FNV
Paladin Cross ; The BoS bunker
Fawkes ; Jacobstown
Jericho ; The Atomic Wrangler or maybe that brothel in Westside seem like his cup of tea.
Clover ; Cottonwood, if you're Legion-Friendly. Chilling in the Thorne and getting off on the senseless violence if you're not.
Dogmeat ; Old Lady Gibson's. Maybe he finds a nice girlfriend there.
That Mr. Gutsy ; No idea for this one.
Charon ; Also no idea.
FNV Followers in FO3
Veronica ; Rivet City science lab actually seems more fitting than either of the BoS factions.
Cassidy ; Moriarty's in Megaton, drinking herself to death
Burke ; I expect he'd just want to head home and scalp him some Legionairres. Not sure where he'd feel comfortable in the CW.
Arcade ; Rivet city science lab, again.
Danny Trejo Ghoul Guy ; Underworld
Rex ; Absolutely no clue. Maybe he'd hang out with Butch in the Muddy Rudder? Butch is kind of Elvis-lookin'
Lily ; Underworld
If FO3 companions are scattered on first entry to the Mojave...
Paladin Cross ; The BoS bunker, unavailable until you gain entry.
Fawkes ; Hiding in Black Mountain, friendly to the locals until the player shows up shooting.
Jericho ; Doing a little raiding out of the NCRCF or one of the Primm gangers, perhaps? Happy to turn coat if the player shows up blasting, happier to leave his new gang amicably if the player's friendly with them.
Clover ; Now the property of Jessup, but will eagerly stab him in the back if her rightful owner shows up and hostilities ensue. If the situation is resolved peacefully, she'll return to the player's ownership.
Charon ; Also the property of Jessup, but will attack the player if hostilities ensue ; if the situation is worked out peacefully Jessup will hand his contract back with the lighter. Alternatively, will switch loyalties back to the player if Jessup can be killed and the contract looted from his body quickly enough.
Dogmeat ; Sat at the player's grave and cried until that cowboy robot dug him up. Sat in Doc's operating room and cried until the player woke up.
Mr Gutsy Guy ; Sitting in the graveyard in non-operational condition. Requires a fetch-quest of some fission batteries or scrap electronics to get him up and running again.
Any suggestions or contradictions?