First of all, congratulations for this plugin and for the "twins" Facebook and Google Connect.
I wanted to inform you that the unlik url is wrong, because action is missing.
In line 517 of nextend-twitter-connect.php code is:
return '<a href="'.new_twitter_login_url().'&redirect='.new_twitter_curPageURL().'">'.$new_twitter_settings['twitter_unlink_button'].'</a>';
instead it should be:
return '<a href="'.new_twitter_login_url().'&action=unlink&redirect='.new_twitter_curPageURL().'">'.$new_twitter_settings['twitter_unlink_button'].'</a>';
Regards.
Davide
http://wordpress.org/extend/plugins/nextend-twitter-connect/