I missed the Wrath of the Lich King alpha explosion, but looking over the proposed spells and talents, I noticed an interesting proposed change. New talents and spells are available that refresh the duration of Damage-over-Time effects, such as Corruption and Shadow Word: Pain. While some of these effects are delivered by direct damage spells, the interesting and impacting change that struck me was its inclusion of channeled spells.
With the proper talents, Mind Flay would refresh Shadow Word: Pain and Drain Life would refresh Corruption. This gives more utility to channeled spells, which normally require its full duration to run for optimum effect. PvP, in particular, requires constant motion which gimps the use of channeled spells. If the proposed changes push through, this means that channeled spells can be used for a short duration in order to refresh existing debuffs. This is an incredible trend that I hope makes it into live as well as extend into other, channeled abilities.