AVAST warns of an improved FB authentication attack currently circulating:

http://blog.avast.com/2013/03/25/fake-facebook-login-pages-spreading-by-facebook-applications/

QUOTE: Another wave of Facebook phishing is spreading among Facebook users. Imagine you get a message from another Facebook user with a link to a new amazing Facebook app. Even if the sender is not your friend, you decide to go to the link. Instead of an application you see a fake Facebook login page.