Password expiration mail template currently has the following variables:

• $username (username/s)
• $daysToPasswordExpiration (days until password expire)
• $changePasswordlink (change password link)
• $admincontact (administrator contact details)
• $deploymenttitle (crowd deployment title)
• $date (message date)

$username should be the actual account username, currently it appears to be FirstName LastName.  To match the other templates $firstname and $lastname should be added to allow for more verbose emails if wanted.