IBM updated the Technote 7018591 (Detailed System Requirements - Sametime Standard 8.5.1 Windows) in the past and added Domino 8.5.2 now.

So according to the technote Domino 8.5.2 is now supported as:

- Directory Server

- LDAP Server

- Web Server

in combination with Sametime 8.5.1.1.