[reg29]

When I click on a link I see another person's email address in the login box. I assume it's a facebook user's email.

See these two examples :

http://www.facebook.com/login.php?next=http%3A%2F%2Fwww.face...

http://www.facebook.com/login.php?next=http%3A%2F%2Fwww.face...