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
Mac OS X Services in Snow Leopard
Mac OS X Services let one application supply its powers to another; for example, a Grab service helps TextEdit paste a screenshot into a document. Most users either don't know that Services exist, because they're in an obscure hierarchical menu (ApplicationName > Services), or they mostly don't use them because there are so many of them.
Snow Leopard makes it easier for the uninitiated to utilize this feature; only services appropriate to the current context appear. And in addition to the hierarchical menu, services are discoverable as custom contextual menu items - Control-click in a TextEdit document to access the Grab service, for instance.
In addition, the revamped Keyboard preference pane lets you manage services for the first time ever. You can enable and disable them, and even change their keyboard shortcuts.
FileVault Passwords Potentially Logged in Plain Text