Even my need also also similar. I do not want users to share the details of this site with anyone. Uninvited users are not allowed to private forum, but i still dont want users to be able to tweet or link to facebook for confidentiality purposes, esp say if i am doing closed beta tests.
I would like that too. We would use UserEcho as the feedback platform of an enterprise web application and would not want our users to share on twitter and facebook so easily.
Admins will be able to choose in forum settings
switch feedback sharing shortcuts ON/OFF.
You can configure it in settings->forum->setup->show feedback sharing.