Although details are still appearing, Sophos is reporting that a particular combination of circumstances can result in FileVault passwords being exposed in plain-text log files. The combination is somewhat unlikely — the Mac had to be using FileVault 1 under Mac OS X 10.6 Snow Leopard, be upgraded to 10.7 Lion, and then updated to 10.7.3, all without switching to FileVault 2. Nevertheless, if this applies to you, change that password! follow link
Avoid Simple Typos
If, like me, you find yourself typing 2911 in place of 2011 entirely too often, you can have Mac OS X (either Lion or Snow Leopard) fix such typos for you automatically. Just open the Language & Text pane of System Preferences, click the Text button at the top, and then add a text substitution by clicking the + button underneath the list. It won't work everywhere (for that you'll want a utility like Smile's TextExpander), but it should work in applications like Pages and TextEdit, and in Save dialog boxes.
FileVault Passwords Potentially Logged in Plain Text