From time to time as the product manager for Oracle Solaris Virtualization I get asked by customers which virtualization technology they should choose. This is probably because of two main reasons.
Understandably there is occasionally a lot of angst around this decision but, as always, with Oracle Solaris there is good news. First the choice isn't as complex as it first seems and below is a diagram that can help you get a feel for that choice. We now have many many customers that are discovering that the combination of Oracle Solaris Zones inside OVM Server for SPARC instances (Logical Domains) gives them the best of both worlds.
Second with Unified Archives in Oracle Solaris 11.2 you always have a way back. With a Unified Archive you can move from a Native Zone to a Kernel Zone to a Logical Domain to Bare Metal and any and all combinations in-between. You can test which is the best type of virtualization for your applications and infrastructure and if you don't like it change to another type in a few minutes.
BTW if you want a more in-depth discussion of virtualization and how to best utilize it for consolidation, check out the Consolidation Using Oracle's SPARC Virtualization Technologies white paper.