Sidebar “Wrapper” Plugin/Widget?

You can use the WordPress widget API to create a custom widget containing your PHP script.

Very simple example:

class shoutcast_widget extends WP_Widget {
    function shoutcast_widget() {
    $widget_ops = array(
        'description' => 'Describe your widget here'
    );
        parent::WP_Widget(false, 'Name Your Widget Here', $widget_ops );  
    }   
    function widget( $args, $instance ) {
        extract( $args );
        extract( $instance );
        echo $before_widget; ?>
            <h3 class="widget_title">Your Widget Title</h3>
        <?php

        // Your Custom PHP Script Here That outputs the display
        echo $after_widget;
    }
}
    register_widget( 'shoutcast_widget' );