In cataclysm we wont be using "land mounts"anymore because we are going to be able to fly everywhere except in battlegrounds, so why can't we use the horde mounts if you are alliance or the Alli mounts if you are horde ? Well, I guess that you are thinking ; "duh , we can't use them because we are enemies and there's no way to gain reputation with the opposite faction and obtain the mounts." Well, there's a solution for that. Cataclysm offers us a chance to do it. We have to take it, there's no other way. Now let me explain.
everything it's getting destroyed, our lands are changing. Imagine people in panic, houses destroyed and farmers losing everything they have. So what do they do ? They take their animals and travel to a safer place. from there they will sell the mounts at an expensive price in order for them to rebuild their house . they are neutral characters and don't care if you are horde or alliance. there should be a quest to gain his / her trust . maybe one per race. maybe some non armored models , so it wont show the faction colors.
So...what do you think ?