Bornakk has laid down a "clarification" on what's fair in the Arenas over on the forums -- he says that there's been a lot of questions lately over what constitutes fair play in Arena PvP, especially in terms of win trading.
Unfortunately, his clarification isn't all that clear -- he reiterates that win trading (the act of exploiting the queue in some way to face a chosen opponent, or face the same team multiple times) is against the spirit of the game and against Blizzard's wishes (though his wording gets a little strange when he brings the Terms of Service into it -- we think that by "these actions all fall in line with our fair use clause," he actually means that they violate the clause). He does, however, go on to say that there are certain places in the system where facing an opponent multiple times will happen, and that that's obviously not the fault of players. So that, it seems, is the confusion: players were worried that because of the lack of population in the queue or other factors, that they would be accused of win trading, and Bornakk is saying that's not the case.
Not that Blizzard hasn't been cracking down on win trading as much as possible lately, but the fact is that if there's a way to exploit the system, players will find it and do it. Blizzard says they're working on squashing "agreements" between players, but even then, Arenas may never end up being completely fair.