Power Word: Priest (made by Noobee of Maelstrom, EU) is a movie geared at 70 holy/disc priests new to PvP. I’m really a nut for little instructional videos how-to videos such as this. PvP is one of those subjects where it is often easier to watch-and-learn than read-and-learn.
In the video, there are some basic tips on gearing, talents, and spell casting. There are also strategies on defeating other classes (warriors, hunters, and shadowpriests in this video; more to come in future installations). Others that I have recommended it to have found it quite useful.
It’s been out since June, so if you haven’t seen it yet, give it a go.
Edit: Unfortunately, Noobee got a permanent ban from Warcraft for speaking his disgust about Chastise. (I do not know what he said, just that he got banned for it). Two of his guildmates stated in the discussion thread (linked above) that he will eventually be back to make the sequel to this video, but it may be a while. Now, that is some dedication!