1.6 Leaked Patch Notes

[MongoJerry]

And here is the official info from Blizzard's "Under Development" page:

Got a bit of a scoop from a GM friend: The Blizzard developers are actively working on linking the battlegrounds from different realms to one another. That way, there will be a much larger pool of players playing in the BG's. So, players on low-population servers will no longer be punished for playing on low population servers. Also, even those players who are on high population servers will have many more BG instances to choose from. Heck, maybe guilds will be able to make large raids and enter the BG's as a group? One can hope. Anyway, this is something that they're almost done with. They're just working on how to deal with naming conflicts and other such issues.

Hmmm... just thinking out loud here, but I wonder if that means there will be a cross-realm economy developing soon.

By the way, the GM friend didn't say, but I would guess that one would only play against other realms of the same type. That is, if one played on a PvP server, then one would only fight against players on other PvP servers, and so on.