Ghostly Strike increases your dodge chance by 15%, even if the attack fails to hit.
The ability will be removed at Cataclysm expansion (by the current announcements).
Improvements
[Remorseless Attacks], will give your next Ghostly Strike a 20% or 40% increased chance to crit after killing an opponent that yields honor or experience. The improved crit chance lasts for 20 seconds.
[Lethality] increases the critical strike damage bonus of your Ghostly Strike by 6%, 12%, 18%, 24%, or 30%.
[Glyph of Ghostly Strike] increases the damage dealt by 50% and the duration of its effect by 4 sec., but increases its cooldown by 10 sec.
Tips and tactics
Ghostly Strike stacks with Evasion, giving you a 65% dodge increase when both abilities are active.
Ghostly Strike is not affected by weapon speed normalization, so the best weapons to equip when using Ghostly Strike are slow, heavy hitting weapons such as swords and maces.
Patch changes
Patch 3.3.3 (2010-03-23): If the rogue has a dagger equipped, this ability now deals 180% weapon damage instead of 125%.
[Remorseless Attacks], 
[Lethality]
[Evasion] designed for more regular use.
[Glyph of Ghostly Strike] increases the damage dealt by 50% and the duration of its effect by 4 sec., but increases its cooldown by 10 sec.
