Well, the basic idea is this, somebody is chosen (either at random, or for winning last week or whatever) as a marked man.

This person is given the arena flag - making them available to attack to anybody, serverwide.
Having a regular world announcement every 2 minutes or so, saying: "The Mark was last seen in the arathi highlands!" and restricting the game to azerothian lands, would keep people hot on their trail.

The objective of the marked man would be to kill 5 pursuers, or something like that - in order to win.
If the marked man is killed by another player before he has reached his objective, the person who got the killing blow becomes the new mark.

Now I don't know how easy it is for the GM's to flag someone for arena combat while they are in other locations, or even if it's possible at all, but I've spoken to a few people about it, and many of the heads are looking forward to its possible implementation as an event we can have from time to time.

If after trial, the arena (all of the eastern kingdoms, etc) seems just too big and hard to track somebody down, perhaps we could place further restrictions:
ie: no epic mount travel, don't cross the STV/duskwood border, that kind of thing.

I'd really like to hear from the GM's to see if this sounds like something they'd be willing to entertain