Acquired or Inherited: Acquired
Applied To: Any Aberration, Animal, Dragon, Giant, Humanoid, Magical Beast, Monstrous Humanoid, or Plant with at least 6 Charisma.
Size & Type: Gains Incorporeal subtype. Note that despite losing their Constitution score, the Type is unchanged. (Even the flavor text makes it clear these aren't "true undead".)
Space/Reach: Unchanged
Hit Dice: Max HP appears to be equal to base creature's current HP at time of acquisition. This is probably abusable.
Speed: Fly speed equal to base creature's land speed, or its Fly speed if higher. Perfect Maneuverability. Existing movement modes are not explicitly lost, though being incorporeal may make walking on land difficult.
Ability Scores: Str -, Dex +0, Con -, Int +0, Wis +0, Cha +0 - Net +0, no "penalties"
Armor Class: Lose natural armor, gain ChaMod to deflection, minimum 1.
Skills: Unchanged
CR: 0. Not "+0", but 0.
WotC LA: +0
Our LA: -0
So you gain this template by going through a special portal that sends your body and soul to different destinations. Needless to say, your equipment goes with your body.
Most notably, this template will cost you the ability to attack, and limit you to a single move action each round. You also can't speak.
In exchange, you get incorporeality (with all the usual benefits and drawbacks) and one special ability: Rejuvenation. Whenever you would be "destroyed", you get to make a level check against a flat DC of 16. Success allows the Disembodied Spirit to restore itself in 2d4 days. Though there is also a Ghost-esque "set right whatever prevents it from resting in peace" clause.
And hey, if you decide you don't like being a Disembodied Spirit, you can be restored with Resurrection or True Res. Though you still need your old body (or a piece of it) for regular Resurrection.