How to query custom post types with multiple keys?

Here is example from Codex on using BETWEEN with new format of meta query, which covers multiple fields as well:

$args = array(
    'post_type' => 'product',
    'meta_query' => array(
        array(
            'key' => 'color',
            'value' => 'blue',
            'compare' => 'NOT LIKE'
        ),
        array(
            'key' => 'price',
            'value' => array( 20, 100 ),
            'type' => 'numeric',
            'compare' => 'BETWEEN'
        )
    )
 );
$query = new WP_Query( $args );

See Custom Field Parameters for details.