How do I get the date of RSS Feed?

I have RSS feed link, but I need to obtain date from it. Then determine whether to do something based on how close it is to the current time.

$date = Get_RSS_Date(); 
$currenttime = getdate();
if $data = too far away from $currenttime then don't display RSS feed.

Make sense?

You can use Magpie_RSS function which will return an array of the RSS properties, and PubDate key contains the timestamp.