I suggest that a hook is added so that HTML can be inserted between the Page Title (ie "Edit Post", "Edit Page"), Notices/Messages ("saved successfully, etc") and the Title Editor box (ie. "Enter title here")
Just underneath line 254, something along these lines:
<?php if ( $notice ) : ?> <div id="notice" class="error"><p><?php echo $notice ?></p></div> <?php endif; ?> <?php if ( $message ) : ?> <div id="message" class="updated"><p><?php echo $message; ?></p></div> <?php endif; ?> <strong><?php do_action('post_header_html'); ?></strong> <form name="post" action="post.php" method="post" id="post"<?php do_action('post_edit_form_tag'); ?>>
An action like 'post_header_html' and 'post_header_html-<posttype>' would allow for more flexibility on adding tab systems, and other potential UI improvements in the header.
For a visualization of how I would use such a hook, see:
To Long Didn't Read: I want to be able to echo HTML in this area of a WordPress post page.