I have both twitter and facebook login set up with
-keys in the config file
-all clear from twitter/facebook developer sites
-both sign in options enabled in host settings
-buttons show up fine and ask for permission to share the account

When I authenticate either the twitter or facebook popup, both times I am greeted with either a messagebox (twitter) or one of those java dialogs on the page (fb):

"Single Sign On is deactivated for that User, you need to activate it in your Profile Settings to use that feature."

Now I'm not one to ignore error messages, but I cannot decipher what this one is trying to say. What am I doing wrong here?

I could be wrong, since I don't use either service myself, but I imagine each user needs to setup their profile with their username/id and set an option to use them. Check under My profile->edit profile. If this doesn't help, there are several threads about how to set this up properly, make sure to make use of the forum search to find them.

Please Check the Documentation under Login for Existing Users

Facebook:

http://yafnet.codeplex.com/wikipage?title=Facebook%20Integration&referringTitle=Documentation 

Twitter:
http://yafnet.codeplex.com/wikipage?title=Twitter%20Integration&referringTitle=Documentation 

Hrm. Well I think I understand what this is now. I was probably thrown off by a project I did a while ago that had a whole different approach to oauth.

Thanks for your time and quick responses.