I've compiled some stuff from the forums but not sure if I missed anything. Hope this helps...

Supernatural Skills

Thief magic grandfathered!

New Stat Contest

Finesse uses agility primary, reflex secondary and intelligence tertiary.

Khri

Darken - Stealth boost
Hasten - Chance for RT reduction on attacks
Focus - Agility boost
Dampen - Stealth hinderance reduction
Strike - Backstab boost, melee weapon boost
Silence - Pulsing Invisible
Safe - Locksmithing boost
Avoidance - Reflex boost
Plunder - Discipline, Thievery boost
Prowess - AOE pulsing debuff (engaged) Fear vs Will when hidden, Power vs Will otherwise. Reflex, Tactics debuff (Charm v. Will)
Sight - Perception boost, nightvision effect
Calm - Self dispel, indescriminant
Shadowstep - Same as before
Sensing - Same as before
Vanish - Disengage + Invisible
Flight - Athletics boost, pulsing balance boost
Guile - AOE pulsing debuff (engaged) Charm vs Will. Evasion debuff (Finesse v. Will)
Steady - Bow/XBow boost
Eliminate - Brief -noshield -noarmor debuff (Finesse v. Reflexes)
Serenity - SvS barrier vs Will
Liberation - pulsing -web/-immobilize
Elusion - Evasion/Brawling boost
Sagacity - Physical damage ward

Khri Combinations

Secure - Focus/Safe/Sight - Additional chance not to blow a box
Speed - Avoidance/Plunder/Flight - Something nifty for PvP, not terribly useful otherwise
Spar - Strike/Steady/Elusion - Thrown weapons boost
Skulk - Darken/Dampen/Shadowstep - 0 second sneak in urban areas, +nolocate
Prescience - Sensing/Serenity/Sagacity - Passive spot, additional guard avoidance/justice bonus
Cunning - Hasten/Guild/Liberation - Charisma/Tactics boost

Ambush

Stun - stun/unconscious depending on success (Power v. Fortitude)
Slash - Prevents engaging/retreating/movement, may cause target to kneel on high success (Finesse v. Reflexes)
Choke - Single target debuff - Stamina (Finesse v. Fortitude)
Screen - AOE (range limited) debuff -perception, minor pulsing RTs (Finesse v. Reflexes)
Clout - Pulsing concentration drain (Finesse v. Will)
Ignite - (I forgot... Placeholder) (Finesse v. Reflexes)

The biggest factor in ambush success is currently the stat contest. You can still successfully land an ambush even if spotted if the contest is tilted in your favor.

Meditate Khri

Significantly improves magic learning on the next khri pulse.

Backstab Changes

Backstab has a built in accuracy bonus. It does not vary based on hiding/backstab skill check success.
Backstab will receive a larger damage bonus the more you succeed your backstab/hiding check by. This caps at about 33% more skill than the enemy's defenses. For example, 600 backstab/hiding against a 500 defense sky giant caps the bonus.
The first backstab on a target now receives a massive damage bonus.
DPS-wise, a backstab has a base potency greater than a lunge. This is before either damage bonus.
The defense penalty from backstabbing was reduced.
A backstab against an at-circle foe was doing over 8x the damage of a thrust, with much higher accuracy.
Backstab is now primarily a puncture maneuver.