WOW - The 2v2 Queue Times : World of Warcraft General Discussions

There is a change in 2.4.0 that will allow the servers to kick up more arena instances in a shorter amount of time, generally lowering the amount of time it will take to get into a game with an equal amount of people queuing. We want to avoid calling this a one time "queue cure" as we're still not entirely certain how the changes will affect queue times under full load. Especially considering the increase in activity we see with any major patch release.

I think they're guaranteed to have some effect, but if it isn't an adequate impact we'll need to make further adjustments.