causes trouble for me. I may enter a password "foo" and save it. If I come back to the Email Settings page to change the Mail server (this happens nearly every week) and press save then the password "foo" will be overwritten with the hash which is now stored there.
Only the 3.1.* versions have this problem.
connection-managers-settings.jsp displays still the plain text password, so there's no problem except that one with access to the web console can view it without problems.