As above.
I've tried the FQL query
SELECT eid FROM event WHERE
(start_time > 2011-08-19T03:00:00+0000) AND (end_time < 2011-08-19T08:00:00+0000) AND
((venue.latitude + 0.005 > 23.7490375) OR (venue.latitude - 0.005 < 23.7490375)) AND
((venue.longitude + 0.005 > 90.39463031) OR (venue.longitude - 0.005 < 90.39463031)))
The result I got was
Your statement is not indexable. The WHERE clause must contain an indexable column. Such columns are marked with * in the tables linked from http://developers.facebook.com/docs/reference/fql
Is there a way to get this information using either facebook or some other database service?