Talking about Apple and security in the same sentence is only done by those who have never attempted to support them in an enterprise.
FileVault? Seriously?
You're talking data security, I presume, not OS vulnerability, which was the topic. Nevertheless...
Have you looked into TrueCrypt? It's not a panacea, but it's a heck of a lot more capable than FileVault, and allegedly more flexible and stable in most comparable situations.