Well, this is really a first for Blizzard (ever since the game was initially released and the class descriptions written, anyway). Ghostcrawler has noticed that there are a lot of questions saying people don't understand what the role of the Priest is right now. Accordingly, he has gone and written up "what [Blizzard] think of as the role of the priest class." I think it's interesting enough to reproduce in its entirety; I'll go through it one paragraph at a time.
The priest is a caster class that uses Holy and Shadow magic. Priests can only wear cloth armor and have a limited selection of weapons, but do most of their damage and healing from range. They make up for their low armor with spells that offer protection and healing.
This is obvious enough to anyone who has been a member of the Priest community long enough ("one tough cookie," anyone?). Still, it's nice to see it spelled out, I guess. And it does emphasize that our defenses are more in terms of "protection and healing," instead of in terms of escape skills like a Rogue (for example) has.