I couldn't find the answer to this question by google-ing, and I figured someone here must know: When Protoss die, what happens exactly? Psyonic energy is released...thats about all I know. What happens? Do they leave behind bodies? What does Lore say about this?
They leave behind a body. (This happened in several novels, and there's a dead protoss on the cover of either Insurrection or Retribution.) Blizzard (on the battle.net Q&As) and the Dark Templar Saga both covered this, very explicitly. Link: http://starcraft.wikia.com/wiki/Protoss#Medical_Care
For Zealots at least, they don't actually die, the blue spirit release is the result of a teleportation beacon implanted in their armor, which teleports critically injured protoss back to some sort of infirmary where they can recover before returning to the battlefie- D'oh, Kimera beat me to it. I'm pretty sure the blue flash is different for high templar though - their spirit is released from it's mortal coil to ascend to unity with the Khala
Zealots, Dark Templars and High Templars are teleported, not really dieing. Dragoons do die, the machinery that supports their already crippled lives is destroyed.
Fenix isn't coming back. Repeatedly confirmed by Blizzard, most emphatically at the lore panel at BlizzCon 2008. Dead is dead.