There is a list of priest specific sites on a sticky on the general board found here:
http://wow.allakhazam.com/forum.html?forum=21;mid=1203382460178386883;num=60;page=1
Scroll down the list to find class specific websites.
Through the Elitist Jerks website you can also find a post WOTLK discussion on Discipline PVP builds here:
http://elitistjerks.com/f77/t38869-pvp_disc_spec_discussion/
Hope this helps and good luck.