Zones and Branded Zones are indeed a useful feature for getting multiple separate lightweight partitions in your system. They are probably directly analogous to Linux's OpenVZ and the Containers namespace solutions which are slowly trickling into the mainline kernel.
However I'm not sure how much real traction they have. They do allow better resource utilisation that full virtualisation but I suspect the margin is being chipped away. The market seems to have bought into full virtualisation a lot faster than these container based approached.