Infinite for loop on FB Json answers

If you submit an ajax query to Facebook like

http://www.facebook.com/ajax/typeahead/first_degree.php?__a=1&filter[0]=user&no_cache=0&stale_ok=0&viewer=&token=&lfe=1

they will return a valid json enclosed in a piece of code which goes on infinite loop.

Kinda of naive filter for people poking around and doing naive eval of json fragments? This happens for all the json queries submitted to Facebook.

for (;;);{"error":0,"errorSummary":"","errorDescription":"","errorIsWarning":false,"silentError":0,"payload":{