Yes and no... You'd need separate applications for each social network for each site. For apps like Facebook and LinkedIn, they will return a unique user ID for each user based on the Application.. which means you can't easily 'share' the account information between sites.
What you can do is use one of many different extensions to create a user on a 2nd Joomla site. Then, with JFBConnect configured to automatically link users by email address, they're accounts will be automatically connected when they try to login to the 2nd site. They won't even have to know that it's a separate account.
That second option is what multiple sites we know of use. It's not 100% perfect or infallible, but it works well.
I hope that helps explain,
Alex
This is more of a feature request than anything else
