Add Search Option

You have to create some custom search form and an custom query.

Pseudo code:

if(function_exists('pronamic_google_maps_mashup')) {
	$lat = $_GET['lat'];
	$lng = $_GET['lng'];

	$latLo = $lat - 0.25;
	$latHi = $lat + 0.25;
	$lngLo = $lng - 0.25;
	$lngHi = $lng + 0.25;

	$query = new WP_Query(array(
		'posts_per_page' => -1 ,
		'meta_query' => array(
			array(
				'key' => '_pronamic_google_maps_active',
				'compare' => 'IN' ,
				'value' => array('true', true, '1')
			) ,
			array(
				'key' => '_pronamic_google_maps_latitude',
				'compare' => 'BETWEEN' ,
				'value' => array($latLo, $latHi)
			) ,
			array(
				'key' => '_pronamic_google_maps_longitude',
				'compare' => 'BETWEEN' ,
				'value' => array($lngLo, $lngHi)
			)
		)
	));

	pronamic_google_maps_mashup(
		$query ,
		array(
			'width' => 579 ,
			'height' => 600
		)
	);
}