Unconfirmed for PS3, haven't seen this posted anywhere else.

On the Blindsighted quest, head to the dwemer ruin and proceed to both Brynholf and Karliah. Speak to Karliah and have her follow you. Draw your weapon. At the top of the stairs, both Brynholf and Karliah will sheathe their weapons, indicating they have stopped following you.Talk to Karliah again and have her follow you. Immediately after, draw your weapon and backpedal. Karliah and Brynholf should move a step forward. Keep doing this and eventually both Brynholf and Karliah will bypass the event where they stop following you, granting you two permanent Nightingales, much like the DBI Bug. Have fun!