OD+ used to require SDMCP.EXE for the systray, but starting with the 1.58 beta it was no longer required.
From the History text.......1.58 beta
-Completely redone system tray mechanism, which is more lighweight and does not require any
additional resident EXE (that’s right, sdmcp.exe will be a thing of the past

) System tray
will not currently work on 64-bit versions of Windows, but they do work with Windows Vista, including
the new "Special" tray icons in Vista.
I believe trayserver.exe is for DesktopX and ObjectBar.