PsiChi - loved the rinse eyes out with Bleach comment... ahhh the mental image is hilarious.
As for a Shadow Priest PvP spec / talent build, you need to do the following:
1. Read the Stickies as the info is there.
2. What size arena team?
~ 2 v 2 you may be okay up until the 1700 bracket.
~ 5 v 5 truly only Disc is viable as you will be focused fired on.
3. What sort of group on the Arena Team and is there synergy?
Do that and maybe some of the scholars and sages will give you a better response as you are not providing enough information for a good answer.