Why/how does Forumosa show me other people I know that use Facebook? To my knowledge, I have not authorized Forumosa or Facebook to connect to each other. I cannot locate any place in settings to remove this connection.
I don’t see your fb deets. 
Every page, just below the Forumosa.com label at the top on the left, shows a Google+ box and a Facebook box. Beside them, it shows 2 or 3 people that I am friends with on Facebook and the comment “and XXX others like this.”
How does Forumosa know who my friends are on Facebook? I don’t think I have authorized Forumosa or Facebook to have any type of connection to share that information.
We don’t know who your friends are on Facebook. What you see is standard code provided by Facebook for websites whose pages want to be liked on Facebook. I don’t even understand how it works - on the index and search pages, I only see 240 people liking “Forumosa”, but in the Temporary Forum, I see over 750 people supposedly liking Forumosa.
W/r/t how that bit of code is able to identify your own friends who have liked the same thing, I imagine its connected to any cookie information that Facebook stores on your computer. When you browse to a website that uses that code (not just Forumosa), the cookie info would help provide that link you describe 
They either do it through a cookie or through shared e-mail addresses in some sort of network tracing program. I guess.
Facebook grew exponentially off such fairly underhand schemes.
Ok, got it. Thanks.
It only does it when you’re logged into Facebook. I think it’s just pulling the information straight from your account there.