Cross realm zones?

Question

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?

Answer 1

The FAQ from WoWWiki should help here:

Shared Areas:

Q. What areas will be shared?

This can vary from realm to realm and relies on how densely populated (or underpopulated) an area is. Capital cities and areas with regularly high populations will not be eligible for area sharing.

Level Restrictions:

Q. What level range do my friends and I have to be within in order to group?

There is no restriction on level ranges. You’ll be able to group with anyone you would normally be able to.

Other Restrictions:

Trading

Q. Will I be able to trade with others I meet?

Trading restrictions are in place much the same as they are in cross-realm dungeons, raids, and battlegrounds.

From experience I have seen different zones that were Cross (X) Realm zones on two different realms I play on. Blast Lands seems common, while I have also seen Stranglethron Vale. Seems the less populated areas on multiple servers get combined.