Bind on Account items and heirloom gear will continue to work the way it does today. We've been told the current heirlooms will work up to level 80, but not past. We'll need to get new heirloom items for that. Those new items will be purchasable through a system similar to what's implemented now, although the specifics are not spelled out yet.
I would assume the heirloom gear now will work on worgens and goblins, however there's nothing stopping Blizzard from including racial requirements on Wrath heirlooms. But I would be very surprised if they did that. In fact (even though I already have a priest) I'm saving up for a full heirloom set for my soon-to-be created goblin priest.
Stats on the heirloom items, just like with all other gear, will change to reflect the new systems coming out with Cataclysm.
Syraleon asked ...
"Some time ago I heard that Blizzard was thinking of implementing the ability to send mail and BoA items to cross-realm and cross-faction characters on the same account, Is this still in the works?"
You can already send BoA items cross-faction. You currently cannot send items cross-realm, however that's something Blizzard has said they'd like to do in the future, but they don't have a time-frame for it and are not even saying it'll happen in Cataclysm. In other words: it might never happen so don't count on it.
Manouch asked ...
"While we know that some old instances are going to be revamped, will the lore of those change too?"
We don't know yet, but given the game world is changing, I would assume the stories for old dungeons that we're running again would move forward as well. There has to be a reason we're going back clear Deadmines and Shadowfang Keep again. The new lore/stories will tell us this -- we just don't know what that lore is yet.
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