Sid Shuman of the official PlayStation Blog tested the Vita handheld's Remote Play experience for Destiny during its popular Beta period. Remote Play will allow players to stream the PS4 title to the vibrant 5-inch screen on the Vita, perhaps while they're in the bedroom or bathroom.
It should be noted that the Remote Play feature, for the month of July, was used the most specifically for Destiny.
If you're curious, Bungie has shared the control scheme for Destiny on PS Vita, where the touchscreen has been split into three areas: the left side throws grenades, the right side does a melee attack, and the center part summons the ghost and returns your character to orbit.