Wrath of the Lich King (and also the upcoming patch 3.0) includes a new tradeskill: Inscription. Inscriptionists will be able to create scrolls, off-hand items, and parchments to help enchanters sell their wares. However, their key crafted item comes in the form of spell/skill enhancing Glyphs.
Every non-inscriptionist character has six Glyph slots they can use to enhance themselves. There are three major and three minor slots; of which you can mix and match appropriate Glyphs. An image of the Glyph interface is shown above (the center slot is thought to be for Inscriptionists themselves as a tradeskill perk).
Some of the various Glyphs enhance existing abilities, while others add utility to skills that change its function completely. The current Rogue Glyphs come in 3 major flavors: cooldown/energy cost reduction, range increase, and damage/effect increase. After the cut, let's explore these groups individually.
Cooldown/Energy Reduction Glyphs:
Adrenaline Rush, Preparation, Gouge, Blade Flurry, Shiv
The Rogue's two largest cooldowns, Adrenaline Rush and Preparation, both receive CD reduction Glyphs, to the tune of 60 seconds and 2 minutes, respectively. This can become key in long PVE encounters, allowing more Adrenaline Rushes per fight. It also provides the Rogue with more cooldown flexibility in the arena, where matches will often last over the reduced CD of 8 minutes on Preparation.
The Gouge and Blade Flurry Glyphs reduce the cost by 10 energy for the former, and 100% for the latter. Improved Gouge already yielded an energy surplus for rogues when used on a target, as the rogue would generate more energy during the incapacitation than they spent to cast it. This will increase that energy bonus, making the Gouge Glyph a very easy call for any rogue who picks up Improved Gouge.
The Blade Flurry Glyph adds more burst potential to the spell, as the savings of 25 energy means almost an additional Sinister Strike during the BF duration, which is then doubled against the two targets affected. Double the fun with none of the cost!
The Shiv Glyph also reduces the energy cost of the skill by 5, although the cost of Shiv varies based on the speed of the off-hand weapon. Shiv is the core Rogue ability we receive at 70, and has a use for all talent specs, in both PvE and PvP situations. I see this Glyph as being especially valuable to a Rogue in the arena, where Shiv may be your #1 used ability, depending on your opponents. Definitely try to pick up this Glyph if you have the resources.
Range Increasing Glyphs:
Ambush, Deadly Throw
Ambush and Deadly Throw both receiving 5 yard range increases via Glyphs. The Ambush Glyph will be a must-have for any Shadow Dance-specced Rogue, as getting off those Ambushes on moving targets will be a major factor in Shadow Dance's effectiveness. The Deadly Throw increase is not as exciting as most targets aren't able to escape the Rogue's proximity easily. This Glyph appears most useful against Druids and Shamans, who both have speed increasing escape mechanisms. However, as a Major Glyph, I do not see this one being used very often. Though, there is something to be said for landing a Deadly Throw silence from 35 yards away on a mage who though he had you finished...
Damage/Effect Increasing Glyphs:
Hemorrhage, Backstab, Sinister Strike, Crippling Poison, Ghostly Strike
The Hemorrhage and Backstab Glyphs both increase the affected skill's damage, but in an interesting way. The Hemo Glyph increases the Hemo debuff's bonus damage by 40%, which Hemo now consumes 1 charge of when used. This ends up becoming equivalent to a +30 damage weapon enchant on both your weapons, as 40% of the 75 damage bonus (at 80) is 30 damage. That's equivalent to ~160 AP for your Main Hand, and ~280 AP for your off-hand, assuming standard Rogue weapon speeds. This is a great Glyph and any rogue with Hemorrhage should pick this up first. With the addition of this Glyph and the new talent Slaughter From The Shadows, the dominance of Hemo in many playstyles seems imminent for WotLK.
The Backstab Glyph is another attempt to give dagger Rogues more viability in WotLK, as they were the least common weapon used by Rogues during TBC. This Glyph causes Backstab to hit 20% harder when the target is stunned or incapacitated. With a 45 energy cost (with Slaughter From The Shadows) and Rogues having many stuns/incapacitation abilities, this can definitely give dagger Rogues an easy-to-use burst ability.
The Sinister Strike and Crippling Poison Glyphs are also affected in interesting ways. The Sinister Strike Glyph adds a 40% chance on Sinister Strike hits to generate an additional combo point. This is a very important Glyph to any combat rogue, as it can add completely new combo point rotations, and gives the combat specialization more burst options as a whole. Every combat Rogue will want to snag this Glyph. It's interesting to note that this Glyph currently stacks with Seal Fate: a critical Sinister Strike could potentially generate 3 combo points. Sweet!
The Crippling Poison Glyph is likely to be changed in the near future, due to the changes to the poison mechanics, the removal of Infectious Poisons, and the rebalancing of the Deadly Brew and the Improved Poisons talent. It currently increases the chance for Crippling Poison to be applied by 10%, but look for this Glyph to be changed drastically or removed altogether, depending on how Blizzard decides to balance Rogue poisons.
The Ghostly Strike Glyph is fairly complicated, so I'll break it down into pieces: It increases the overall damage done by Ghostly Strike by 40% (the base is 125% weapon damage), it increases the duration of the dodge bonus by 4 seconds (the base is 7 seconds), and increases the cooldown by 10 seconds (the base is 20 seconds). This Glyph is definitely the biggest change to a single spell that Rogues will see.
Having Ghostly Strike hit for 175% weapon damage is huge, making it the highest damage-per-energy spell a Rogue can have. The increased length of the dodge bonus also makes it more useful for tying it with Evasion, allowing a rogue to achieve near unhittable status for 11 seconds. The cooldown increase is unfortunate, but by making Ghostly Strike such a potent damage attack, I see the tradeoff as well worth it. A Cold Blood (critical) Ghostly Strike (175% weapon damage) while under the Master of Subtlety bonus (10% damage) when the target is in Dirty Deeds range (20% damage) and is in an Improved Kidney Shot (9% damage) may be the burst that non-Mutilate Rogues have been lacking in The Burning Crusade. Finishing off wounded targets never felt so good!
That covers the complete set of Rogue Glyphs currently known to beta testers in WotLK. A few may be tweaked for balance purposes, but for the most part, this is what we can expect come November. Planning out which Minor and Major Glyphs you'll be using will be an important step in leveling to 80. However, I wouldn't go gathering materials yet, as it remains to be seen how strong each Rogue specialization will become.