It was announced that along with the release of Mists of Pandaria, many zones throughout the world of Azeroth would become cross realm zones, allowing players from multiple realms to quest in the same zone, cross realm.
This means that when players enter a zone, they will be able to see players from other realms and can party up with these players within these zones.
Is there a list of which zones are in fact cross realm?
Are players only included in a cross realm zone if they're level appropriate for the zone?
Are realms from different regions included in cross realm zones?
Are there any other known restrictions or limitations to the system?