mental ray for 3ds Max 2015 SP2 has been released several weeks ago.
It ships with mental ray version 188.8.131.52.
Several issues were fixed as far as mental ray is concerned:
- mental ray hang when rendering an empty scene
- precision problem when using Arch & Design related to computation of glossy samples
- subset pixel rendering not showing up in rendered frame window when using mental ray
The new NVIDIA GPU Maxwell architecture is not yet supported, but we plan to release a patch very soon. Stay tuned!