From Facebook Developer Wiki

What permissions do I need to run this, can I use it for analytic purposes on a fan page, will I be able to get the current location of fans?

You don't need any permissions to use this call. It works only on users, not Pages. If you get the UID for a fan (say, by using pages.isFan), then you can make this call on that UID and get the demographic info you want. Pete -- 563683308 11:54, 5 November 2009 (PST)