On the technical side, I've been using the Facebook Toolkit from Codeplex and this link on stackoverflow was very useful for working out the cookie confusion: http://stackoverflow.com/questions/323019/facebook-connect-and-aspnet
Currently, it's all gone quite smoothly :)
The only problems I've had:
- My skin didn't initially specify XHTML - so I had to add a .doctype file to my skins directory - if your skin is called AAA.ascx then you need to add AAA:
[![CDATA[ [!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"] ]] ]
- In order to add the xmlns for fb I did have to change the default.aspx code from DNN - it's not a big change, but it's still a bit sad I have to change the core :(
- I messed up the ordering of the facebook elements at one point.... for clarification, make sure that FB.init("API_KEY_HERE", "/dnn/connect/xd_receiver.htm"); is the last thing seen on your web page - not the first!
- I've been fighting with the lack of documentation - facebook seem to be relying on us dissecting their runaround example app...
- I've hit some problems with API calls resulting in "Session key expired or no longer valid" - but these are basically due to the user logging out of facebook - easy to workaround.
- Similarly when the user has logged out of facebook I've hit some problems with facebook's automatic buttons (e.g. with fb:login) - but again these are easy to workaround - you just use your own facebook links instead of the automatic buttons.