The new Solaris Express 4/06 (Nevada build 36) introduces among others the Zone migration feature.
The feature is actually able to move a non-global zone from one host machine to another, requesting a detach and re-attach.
It will possibly be included in upcoming Update 2 (Solaris 10 6/06), which is expected in June.
Download Solaris Express 4/06 here.
Note: If you feel confused about differences between Solaris 10, Solaris Express and OpenSolaris be sure to check this post.