Oracle considers Solaris 10 Zones as Hard Partitioning which means:
"So long as your Solaris 10 Container is tied to a resource pool limited to a number of CPUs which is less than the total number in the server, you only have to license for the number of CPUs which can be in the resource pool, not the whole server."
This is really great for consolidation on Solaris.
Original post you can find here.
And Oracle document on partitioning here.