CoreStorage in Apple Mac OS X 10.7 before 10.7.2 does not ensure that all disk data is encrypted during the enabling of FileVault, which makes it easier for physically proximate attackers to obtain sensitive information by reading directly from the disk device.
http://www.securityfocus.com/bid/50085
http://support.apple.com/kb/HT5281
http://support.apple.com/kb/HT5002
http://lists.apple.com/archives/security-announce/2012/May/msg00001.html
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00003.html