I’ve recently been leveling my Alliance Protection paladin in the Southern Barrens. This is one of the zones in Cataclysm that has active Horde versus Alliance conflict as the central theme of the zone. Like the Redridge Mountains zone, it is a fairly active place with a series of events that is seen completely different by the factions involved.
Note: This reaction to the zone does have an Alliance bias. The Alliance character that went through Southern Barrens does not have access to the Horde faction quests. At this time I can only speak from the Alliance point of view.