I know they have been hinted at before, but list from the EU forums, but I translated the post to American English ;):
Here are the Honor changes that will be introduced with The Burning Crusade:
Honor:
Players participating in Battlegrounds and outdoor world pvp gain honor points (by killing players and getting bonus honor from battleground or world objectives).
Players will be able to spend honor points on special honor rewards.
There are lots of honor rewards (armor, jewelry, trinkets, gems, weapons, mounts, etc), that include totally new stuff for level 70, including all the old stuff from battleground reputations and the old honor rewards.
The level 70 honor rewards are not currently planned to have item levels as high as the best raid or arena items.
Arenas:
If you're on an arena team, you gain arena points at the end of each week based on your arena team's rating (higher rating equals more points, lower rating gives you fewer points).
You spend arena points on arena rewards, found at
http://forums.elitistjerks.com/viewtopic.php?id=8575
Arena rewards will all require level 70. And it will be seriously phat lewt, which will also most likely be more PvP oriented.
The arena rewards will include 5-piece armor sets and weapons (but not other stuff like gems, mounts, trinkets, jewelry, etc).
After the Expansion, the old Honor system will be completely removed and players who achieved ranks in the old Honor system will be able to choose to display their highest gained Rank as a title. We are interested in reintroducing these titles in the future but we have no specific plans in place yet.
There will be new titles that players can earn through the Arena system and these titles will only last for the duration of each Arena Season.
Arenas are currently planned to be cross-realm just like the Battlegrounds. The Battlegroups should be the same as they are now.