Huh, the rumors I've heard all say Joyent's use of illumos is not long for this earth.
They continue to port code to Illumos (i.e. KVM, continued work on Pluribus port of bhyve, etc.).
SmartOS is what their data centre orchestration solution gets built on-top of.
You can see their changelog for SmartOS they are quite active: https://us-east.manta.joyent.com/Joyent_Dev/public/SmartOS/s...
Development of SmartOS and Triton Datacentre occur under their joyent organisation on GitHub.