Lots of new changes posted... Shadow priests not only no longer the main mana battery - mana regen totally revamped:
This and a ton of other interesting changes coming in this next patch, before the WotLK release - read up on it here.
In addition to this change, we also needed to address the "mana battery" roles in a raid. The mana regeneration effect they grant is no longer limited to their own party, and it no longer depends on the amount of damage they deal. Each time they trigger the mana regeneration effect, 10 people in their raid group will receive a buff which causes them to regenerate 0.5% of their maximum mana each second. This buff, Replenishment, will be given preferentially to raid members with the lowest mana, but will re-evaluate which raid members receive it each time it is fired. Replenishment is provided by Shadow Priests, Survival Hunters, and Retribution Paladins.