Not according to the 4th Editon Codex, and the 2nd Editon (Angels of Death) states that only the Supreme Grand Master of the Dark Angels speaks to Luther.
I don't know it speaks of exactly how paranoid and secretive the Dark Angels are, the Ultramarines adhere strictly to the Codex and the DA take the concept of need-to-know to the most extreme levels.Well the direct quote from the codex is "As Supreme Grand Master, Azrael alone is privy to the greatest secret of all. At the very heart of the Rock is a cell, shielded by metre upon metre of adamantine armour and inscribed with the most potent runes of warding. Withing, kept alive for ten thousand years inside a stasis field, languishes the broken Man who was once Luther."
So yeah, only him. Something that irks me a little, i think at least the Masters of the Deathwing and Ravenwing as well as the Grand Master Librarian and Master Interrogator-Chaplain should also know