Good news for Shadow Priest in some recent blue posts, firstly regarding their current DPS or lack thereof:

Quote from:Ancilorn
We do recognise that Shadow priest single-target damage is on the low side. In 3.3 we plan to have some changes coming to bring them up a bit. Most of the changes will likely be made [...]

We are proud to present a brand new feature: World of Warcraft hit rating calculator is available now at http://www.wow-track.com/hitcalculator.php
Keep in mind that it’s still in beta testing phase, but so far everything seems to be working properly.
Please feel free to comment what you like or dislike, we’re looking forward to hear your thoughts [...]