Being derived from Illumos and in-turn from Solaris, SmartOS does ship with ZFS support, DTrace, and other former Sun Microsystems technologies.
"Joyent, the global provider of cloud computing software and services, today announced that it has ported KVM to its operating system, SmartOS. SmartOS turns any server into a highly efficient, multi-tenant application hosting platform. The open source project offers innovative tools for application developers looking for reliable, resilient storage and efficient virtualization that Joyent has tuned and hardened for modern, data-intensive real-time (DIRTy) application deployment."
More details on Joyent SmartOS can be found in this press release.
For those interested in Linux KVM being ported to SmartOS, see this DTrace.org blog post. "In the fall of last year, the imperative became clear: we needed to port KVM to SmartOS. This notion is almost an oxymoron, as KVM is not "portable" in any traditional sense: it interfaces between QEMU, Linux and the hardware with (rightful) disregard for other systems. And as KVM makes heavy use of Linux-specific facilities that don't necessarily have clean analogs in other systems, the only way to fully scope the work was to start it in earnest. However, we knew that just getting it to compile in any meaningful form would take significant effort, and with our team still ramping up and with lots of work to do elsewhere, the reality was that this would have to start as a small project. Fortunately, Joyent kernel internals veteran Max Bruning was up to the task, and late last year, he copied the KVM bits from the stable Linux 2.6.34 source, took out a sharpened machete, and started whacking back jungle..." The ported code of the Kernel-based Virtual Machine can be found on GitHub.
When returning from LinuxCon there might be some Phoronix benchmarks of SmartOS.