gdmlogin from gdm-2.5.90.1-1 tells if the username was valid or not before user enters the password. This should be considered as a security problem. If we want to tell the user when he last logged in, better place might be the Gnome splash screen. Perhaps.
I second this. It's worse than knowing whether a username is valid or not - people with access to a computer could find out when exactly other users logged in to it. Reminds me of Novell Client for Windows' default configuration which is set to pre-fill the username box with the last logged-in user...
*** Bug 118679 has been marked as a duplicate of this bug. ***
Note this is a configurable option and is now turned off by default.
*** Bug 118046 has been marked as a duplicate of this bug. ***