Have you tried it? This was posted in January, but doesn't seem to work anymore.

    curl -A Opera 'http://www.facebook.com/ajax/typeahead_friends.php?u=4&__a=1' 
    for (;;);{"error":0,"errorSummary":"","errorDescription":"","errorIsWarning":false,"silentError":0,"payload":{"friends":[]}}

I have my Facebook profile closed down as tightly as Zuckerberg will allow, so this doesn't return anything for me.