How can I get the Jetpack Image plugin to open links in a new window? [closed]

There is no hook available in the plugin.

One solution is to simply copy this Jetpack Widget and add the target option.

Another is through jQuery, in the file /theme/functions.php:

add_action( 'wp_enqueue_scripts', 'jetpack_widget_wpse_88067' );

function jetpack_widget_wpse_88067() 
{
    wp_enqueue_script( 
        'jetpack-hack', 
        get_stylesheet_directory_uri() . "/js/jethack.js", 
        array( 'jquery'), // dependencies
        false, // version
        true // in footer
    );
}

And in the file /theme/js/jethack.js:

jQuery(document).ready(function($) {   
    $('.jetpack-image-container a').attr('target','_blank');
});