This hit my feed reader this morning...

Atsec information security is pleased to announce the successful Common Criteria Certification of Mac OS X Snow Leopard at EAL 3

Reference: http://www.atsec.com/us/news-atsec-apple-mac-os10-6-common-criteria-evaluation-snow-leopard-184.html

It took me a few minutes to find it, but if you want a certifiably secure mac you need to follow Apple's Admin Guide on their Common Criteria page, I know what I'll be doing later :)