A client would like me to add their Twitter stream to their website homepage, using a custom solution built in PHP.
The Twitter API obviously has a limited number of
array( 'lastrequest' => 123, 'tweets' => array () )
now in your code put a check to see if the timestamp in the datastore for lastrequest is more than X seconds old. If it is then its time to update your data.
serialize and store the array in a file, pretty simple