Based on my own experience and that of many others the most potent combo in 2v2 arenas tends to be a Restoration Druid and MS Warrior. Finding a way to control this combo is the starting point for many teams. The problem we currently have on our 2v2 team is that we are a Restoration Druid and Dagger Rogue combo. We own most others except for this particlar combination which seems to give us a severe beating.

Now this is not to say that others are not very effective as well. In fact we fought a Shadow Priest and Warlock combo today that just was very organized in their crowd control. Their approach was to keep me dotted and chain feared while they worked on mana draining my partner. This approach was very effective and after a long and proatracted battle (Most of which I spent feared and dotted) we lost to these combonation.

While yes the Druid/Warrior team is very, very effective it is not the end all of teams. All teams are very effective if the communication is there and your tactics are very sound. One of the most important things to remember when in arenas is to have a plan in place for each potential combination and spec that comes about.

The really effective teams are those that communicate well and have played at least a few hundred arenas together. This is very important to get to a point of comfort with your teammate. The top teams in arenas have played many matches together and have strategized every combination that they could come across. So do not let the fact that you are going against a warrior/druid combo discourage you. Any team can be beat on any given day. It just may take some work and a really coordinated plan.