Glyph of Fading - Reduces the mana cost of your Fade spell by 50%.
Well, I'm willing to guess this is a Minor Glyph. It's not that great and Fade isn't something you spam, though you'll be using it a lot more in PvP than PvE for sure. In the Wrath beta, Fade currently costs 13% of your base mana, according to Wowhead. At level 80, Fade will cost you around 470 mana, give or take a couple of points. With this glyph, it will cost 235 mana. If you're using a talented Fade every 24 seconds it will be equivalent to roughly an extra 50 mana per 5 seconds. According to a friend of mine, 48.95 mp5 is the exact amount. I didn't really feel like getting that crunchy about it, so I'll take his word for it. You probably won't use it immediately every cooldown, but eh.
As a minor glyph, that's fairly decent, really. It sounds underwhelming, but assuming it is a minor glyph, it's likely not a terrible choice for a PvP Shadow Priest. It'll come down to whether or not vastly better glyphs are available.
Glyph of Shackle Undead - Increases the range of your Shackle Undead spell by 5 yards.
Uh, sure? I don't know. I guess if there were no other useful glyphs for a Shadow Priest in whichever category this glyph is in, I would take it for PvE. Maybe I would toss this glyph on specifically while my raid is doing Naxx or whatever other Undead-heavy raids there will be, since I'll be doing a lot of Undead Shackling there. It has its applications, but I'm certainly not in awe here. I am guessing this is another minor glyph.
Glyph of Levitate - Your Levitate spell no longer requires a reagent.
As a Priest who uses Levitate constantly and is mighty tired of farming up Light Feathers, I say woohoo! Sure, farming the feathers in Northrend isn't that big of a deal since they drop 3-5 at a time, but I'd still rather not have to do it period. Assuming there aren't 3 much juicier glyphs that share the category this will fall in, I will probably use it.
Glyph of Fortitude - Reduce the mana cost of your Power Word: Fortitude and Prayer of Fortitude spells by 5%.
Like Zach said about the Paladin Blessing of Kings glyph, this one is sort of silly. Occasionally you need to hit someone with a Power Word: Fort mid-combat if a boss gibbed them, but you're not often casting it en masse in the heat of battle. Most of the time, if you're casting this spell you can take a drink of water immediately afterwards. I'm not sure I understand the point of this one at all.
Glyph of Shadow Protection - Increases the duration of your Shadow Protection and Prayer of Shadow Protection spells by 10 min.
This one is a little silly as well. Admittedly, I probably would have used it in Mount Hyjal because rebuffing the darn thing during the trash waves just before a boss because it didn't last long enough was annoying. However, Hyjal was a bit of a special case. The pacing of it is completely different from everywhere else. For convenience this glyph might be nice, but it isn't a huge deal. We might also see more raids paced like Hyjal was in Wrath, and if that's the case I might indulge in this particular glyph.
Overall, I'm underwhelmed with this batch of glyphs. It's not a huge, massive letdown because every class is getting a whole load of them, it's no big deal. It's strange to see Blizzard taking the "make a whole slew of throwaway glyphs to fill it out" direction with these but I suppose there really aren't a lot of massively unique things you can do without making any given glyph mandatory for everyone. Still, they can do better than reducing the mana cost on a buff where 5% off of that cost is entirely irrelevant. 50%? Sure, that would make buffing faster even if it's not entirely necessary. 5%? Pfft. Nobody cares.
I'm still chapped about the Mind Flay glyph, by the way.
[ Glyph descriptions via MMO-Champion ]