Brad Fitzpatrick's http://code.google.com/p/pubsubhubbub/ http://code.google.com/p/pubsubhubbub/ can be used for this. ("Subscribe" to a RSS/Atom feed, it does

Brad Fitzpatrick's http://code.google.com/p/pubsubhubbub/ http://code.google.com/p/pubsubhubbub/ can be used for this. ("Subscribe" to a RSS/Atom feed, it does the polling for you, and gives you callbacks when new entries happen.)