I found this respond at the Proboard website. You can sign up there too and learn more about Proboards. I don't know anything about social networks but perhaps you do. Here is what Proboards wrote about social networks:
New feature: Social Login « Thread Started on Oct 7, 2010, 6:38pm » We are currently testing out our new Social Login system here at support.
Using the Social Login system, you will be able to tie your existing ProBoards forum accounts together with accounts from various social networks.
This can be done in several ways:
For existing users, you can go to your profile and select Link your social networks You can logout, and attempt to login using a social account. This will then ask if you wish to link an existing account. If you do not already have a forum account, you can register for forums using your social network account. This will prepopulate the registration system with information available from your social network. This means less work for you (Even if you already have an account, theres nothing to stop you testing this, just remember theres no point to actually making that new account ).
Once you have linked your accounts, if you are already logged into your social network, you need only click your social network icon to log yourself back in.
Log out, try it yourself
Please remember this is just a test, any bug reports or feedback is greatly welcomed