Sorry. I ran across this thread from google and didn't bother to look at the purpose. Feel free to delete my comments.Rather off topic, and mostly irrelevant.
This thread is about specifically setting up the ability for people to log in to your site using Facebook, Twitter or Google. And, actually, a fair amount of people do this. It's not necessarily the case that it is winning you new members, it's not necessarily allowing content to be brought in from the social network, or shared to the social network, but a lot of people prefer to use them to authenticate to sites because it's more convenient for them.
This is a discussion for another thread, though.
I too had this same error and just wanted to report that I had to un-check the Enable Callback Locking tic-box on the https://apps.twitter.com website. As soon as I did that, it started working perfectly!