rails (heroku) app to re-post a user's blog comments to user's Facebook wall?

My web app (rails 3 on heroku) is sort of like the basic blog app used so often for rails getting started demos, extended to host a blog for multiple businesses.

If a facebook user "Tom" writes a comment on the blog for business "Acme", how can my app re-post the comment onto Tom's Facebook wall? And also re-post the comment to Acme's Facebook page?

The public user writing the comment is NOT a logged in User on our system (the business whose blog is receiving the comment is a 开发者_如何学PythonUser).

There is an option for the user to also post the comment on their Facebook wall if you are using the Facebook comments social plugin. Otherwise, you would need to use the Facebook API and have the user authenticate with your Facebook app id and grant you publish stream permission and then you could post to their wall when posting a comment. Or you could popup the Facebook Share dialog via javascript and the user wouldn't need to authorize your application.