[mirashii]

Solaris zones have been around much longer, and have undergone audits and also been used for multitenancy in production for almost 10 years now. The new LX brand may have some new surface that it's worth auditing, but in general Solaris zones are probably, to my knowledge, the most trusted OS-level virtualization system amongst the major contenders. Disclaimer: I was a Joyent customer and have a few friends and acquaintances who work there still.