It looks like in Cata the questline for Wrathgate will end at the cinematic. No more Battle for Undercity. So, if you haven't had a chance to do it with both, or even one, faction you may want to do it before the x-pac.
World of Warcraft: Cataclysm Beta - (English) Forums -> Wrathgate...
World of Warcraft: Cataclysm Beta - (English) Forums -> Wrathgate...