Yesterday's announcements brought two big notes that will be affecting Shadow Priests. The Fear Ward change and the fact that Spell Haste will affect the global cooldown.
The Fear Ward change, like I mentioned in my last post, is primarily a convenience change for PvE. Reupping Fear Ward every 3 minutes when you need to keep putting Shadowform back on afterwards is annoying, and a large mana drain over long encounters. However, it wasn't crippling, so not a very big deal. What this will help the most is PvP, especially arenas. Having an arena match last longer than three minutes isn't unlikely, so you will probably want to put Fear Ward back up at some point throughout the match. Being required to drop Shadowform to do it is sort of a pain, considering both the loss of damage and the mitigation Shadowform supplies you with, arguably one of the Shadow Priest's strongest defenses.
The Spell Haste change is what has me a little excited. I'll admit right away, I haven't crunched any numbers. I'm notoriously bad at breaking down raw stats, I usually just eyeball my gear and take a guess. I'm right or pretty close more often than not but don't hate me too much if my guesses here are completely wrong. If you want to see some raw numbers, you can probably check them out over at the ShadowPriest.com forum.