Late answer
WP core offers a function for that case, that makes it much easier and future proof: Simply map it on each item.
Wrapped up in a plugin
Best used as mu-plugin.
<?php
/* Plugin Name: (#32093) »kaiser« Open "action"-links in post type list screens in new windows/tabs */
function wpse32093_link_target_blank( $actions, $post )
{
return array_map( 'links_add_target', $actions );
}
// Add to each post type
foreach ( array( 'post', 'page' ) as $post_type )
add_action( "{$post_type}_row_actions", 'wpse32093_link_target_blank', 20, 2 );
The plugin is tested and works seamlessly. You can adjust the post types where you want to have it active in the array inside the foreach loop.