Cantrill is one of the people responsible for dtrace, and more or less the only Sun-alumni who's not retired or disappeared (a lot of them stopped blogging when Oracle killed the Sun blogging culture and site/killed Sun). He also was the CTO of Joyent.
Frazelle was one of the people responsible for Docker.
I think Tuck is a finance guy who used to be a sysadmin? And he was COO of Joyent for a while, apparently.