"Not taking credit for this, but I'll share to see if it can be explored more:
If you queue for a dungeon with 1 or more others and finish it, you can wait for other players to leave the dungeon, then leave your dungeon via the teleport button (1 person). That person enters a low level dungeon, then everyone else leaves the original dungeon via teleport. Finally, all group members click teleport to dungeon and everyone appears in the dungeon with spells, itemlevel, and stats scaled to the dungeon's intended level. My group did ubrs with 4 and it's clearly an unpolished feature, as some of our spells & procs were still 90 powered, but everything seemed to be scaled appropriately. The fact that we had epics definitely affected how good the gear was.
I would be interested in people exploring other dungeons & letting us know how it goes. Like which dungeons does it work in, what type gear did you wear, etc.?"