The only things relating to or suggesting Hive thus far have been the Vex. Just going off the way Glimmer sounds, I remember Deej mentioning in one of the blogs that killing certain Fallen separates their ethereal soul from their corpse; there's a possibility this Glimmer is somehow related to that, and if so, could relate to other supernatural/undead occurrences. Space Zombies for example, if something like undead is what they are. Or being booted from an area on death to respawn somewhere else. Souls and such is a bit fantasy/horror for an SF setting, Space Zombies notwithstanding, but, y'know, extradimensional planes of existence blah slipspace blah, jargon. Space Zombies.