[ruuk]

I need to have facebook authentication in my own plugin, do you know how it is possible? I suppose http://xbmc.2ndmind.com/fb your personal project?

Yes it is possible, but it's difficult. It requires a browser, and my attempts to do it without one have been unsuccessful.
My current method involves authorizing the app entirely in the browser via my website. It saves the access token to a database, which addon then retrieves with the supplied pin.
To make matters worse, the token will expire, so the addon has to occasionally log in and get a new token.

For users who are wondering about their stored tokens, they are stored for an hour, and can only be retrieved with the 4 digit pin and a computer on the same IP that authorized, or from a different IP via the new 12 digit pin. The Facebook access token also has an expiration. Also, the email and password you enter are only stored in your addon settings. They allow the addon to log in to get a new token when the old token expires