The top rated team on the US tournament realm is not an RMP, or even a Hunter/DK setup. According to this article on GotFrag, number one is a warlock team.

After so long out of the limelight, many predicted that warlocks would make a comeback. If the American tournament realm is anything to go by, that is coming true. Of the top 30 players on the TR, eight were warlocks, eight paladins, and eight deathknights. Former 3v3 stalwarts, druid and warrior, are nowhere to be seen.

The European realm paints a slightly different picture, but warriors and druids are still off the scale. Interestingly, however, the number one team in Europe is RMP. Three of the top ten European teams play rogue/mage/priest, in fact, compared to none on the US realm.

However, as the article's writer points out, the next phase of the tournament will probably be played in 3.1: "once the four qualifying weeks have wrapped up, patch 3.1 will more than likely have been released." Exactly how that will change the class representation remains to be seen, but it will almost definitely have some effect.