Thank you for this plugin. I have two suggestions for you to consider in your code for 1.4.4.
On line 194:
$s2p_blog_url = get_bloginfo(url);
$s2p_blog_url = get_bloginfo('url');
On line 196, you assume the blogurl doesn't end in a slash. This may not be true. You could therefore creating a short url with two slashes //. In addition, you don't have to have a slash after the domain name and can instead leverage the ? as the delimiter. This will same you one character (and every character helps in systems like twitter).
$short_url = $s2p_blog_url . '/?p=' . $post_id;
$short_url = ((substr( $s2p_blog_url, -1 ) == '/') ? substr( $s2p_blog_url, 0, -1 ) : $s2p_blog_url) . '?p=' . $post_id;