Craig Edmonds put together this picture of ways to recognize fake Facebook email notifications. The second point is very important – HOVER your mouse over the link and LOOK ON THE STATUS BAR to check the real destination of the link to facebook.com website or or fake address like http://facebook.mailspotter.ru
Craig Edmonds wrote up a great description of about fake Facebook notification emails and how to recognize them.
SOPHOS also wrote up a recent warning concerning fake Facebook photo tagging notifications. Please be careful when clicking on these email links – there is a very good chance it is fake.