Check to see if an e-mail address has a Gravatar or not

gistfile1.aw

<?php

function sunset_has_gravatar( $email ) {

	$hash = md5( strtolower( trim( $email ) ) );

	// If not in the cache, check again
	if ( false === $has_gravatar = wp_cache_get( $hash, 'sunset_has_gravatar' ) ) {

		$request = wp_remote_head( 'http://0.gravatar.com/avatar/' . $hash . '?d=404' );

		$has_gravatar = ( 404 == wp_remote_retrieve_response_code( $request ) ) ? 0 : 1;

		wp_cache_set( $hash, $has_gravatar, 'sunset_has_gravatar', 86400 ); // Check daily
	}

	return (bool) $has_gravatar;
}