Use YOURLS (a free GPL URL shortener service) to create short URLs of your posts, or for your BuddyPress groups and users
I'm just posting this thread to confirm that it woks well with wp 4.1 and buddypress 2.1.1 and bbpress 2.5.4
to show the shortlink of topic titles, you should open the file loop-single-topic.php from bbpress template, and insert this line where ever you like to show the shortlink:
<SPAN STYLE="font-size: 8pt">
<?php if (function_exists('wp_ozh_yourls_url')) wp_ozh_yourls_url(); ?>
it's better to have a child theme of bbpress template files instead of editing the core component. you could search for child themes and read the documentations.