I also have looked everywhere...in and out of game. I believe the above person is correct. We get the "go talk to your local priest" instruction at level 10 and 20, but I dont think we acually get quests like the ones pallys or warriors get...ie the long epic type quest for a really nice weapon or peice of equipment. My priest is only level 29 though... The above person appears to have been level 47 at the time of the post. So unless there is one at a higher level than that, I dont think we get them.
I have helped others in my guild with their level 20 class quests, and although they are very long, and take you all over the world, I really thought it was cool that they had them and can now travel much more of the world freely just because I went along and hit every griff master on the way. I hope in the future they give the priests a quest...even if it's just one.