Ganking is ganking, no matter if the player comes from another realm or not, this has been happening since the dark ages of WoW...
About that revenge thing - how am I supposed to get my revenge if I will never see the other person again because who the hell knows if I will ever see them again? :)
ever wonder why all those people roll pvp (Pro Clue: its the realm type), Yes thats right they want to kill you.
Pro Clue: It's not. I didn't roll PvP Realm because I wanted PvP. I rolled because my old friends re-rolled here due to this realm (Kazzak) having a high-pop, good PvE progress and an imbalanced H:A ratio (ie: we barely saw an Alliance toon every few weeks, which I personally just leave him alone, I just ignore him). There were no talk about CRZ when I transfered PvP.
Most people I know had the same idea when they transfered. PvP realm with close to non-existant Alliance demographic? Heck, that's just a PvE realm labeled as PvP!
But, lesson learned. Now I rarely get out in the world (except Pandaria where CRZ is not in effect). My alts only level trough dungeons until lvl85. No problem.
EDIT: Also, keep in mind that pretty much only PvP realms are populated in EU. There's maybe 2-3 medium-to-high pop realms that are actually alive and that are PvE!