Recently, I was given the opportunity to work on connecting to Facebook.
The way I've done it is by using Facebook Developer Toolkit available on Codeplex.
Codeplex - Facebook Developer Toolkit
All that is required on Facebook is to create an application and specify the Connect Url on the Connect tab to a specific URL, obtain the API & Secret key and you are set to go.
More to follow
ps: This has now change as Facebook released their new Graph API.
Further post to come