I think I know how this works, but would like to confirm. Suppose my Hill Giant is equipped with Darksteel Plate, and then is dealt damage by a Deadly Recluse. That’s one point of deathtouch damage. Without the equipment, that would destroy Hill Giant; with the equipment, it doesn’t.
If the Darksteel Plate is unequipped that same turn, will Hill Giant be destroyed?
I believe the answer is No, because nothing in the rules says that “deathtouch-ness” is remembered. All that’s left is that there’s a Hill Giant with one point of damage marked on it, ergo it survives.