Joyent which builds their cloud service on zones and ZFS just announced a new repository with patches against illumos that provides new features and bug fixes:
"Some highlights of the illumos-joyent tree include:
* ZFS I/O fair-share scheduling for zones
* the Joyent brand, which can be used as a template for other non-SysVR4 or IPS zone brands
* Reintroduction of sparse zone images
* Crossbow vnics on demand for zones & non-unique vnic naming (unique per zone, not per system)
* svcs enhancements ( svcs -Z/-z for interrogating zone services, -L for outputting log files directly (no more ls /var/svc/log | grep... ))
* vfsstat and iostat tweaks and ziostat, iostat(1M) for ZFS I/O
* more per-zone IO kstats
* the zonemon utility for zone kernel state troubleshooting
* DTrace enhancements such as llquantize"
I'll guess many of these changes will find it's way into illumos in a near feature. The whole mail from John Sonnenschein can be read here.
Joyent have always been an interesting company and have recruited very talented people after Sun settled. Both Bryan Cantrill and Brendan Gregg are now employed by Joyent so I would not be surprised if they will become one of the larges contributors to illumos.
illumos-joyent at github
Talks I have given
5 months ago