This is the plugin written by Kevin Jardine and funded by Tolumi Adamson (Tcherokee), Marc Idiotter,  Solution Grove (Dave Bauer and is working on additional functions based on this) and myself, to bring it up to date with the latest elgg and Facebook API. 

This now asks for the email address and uses part of the new social graph API.

It also no longer posts to the river during the cron jobs.

Please don't ask me how it works and if you have a problem with it (which I am pretty sure you will not) you are on your own.

About:

A new user who signs up via FBConnect will have their Elgg profile populated with their Facebook profile information and status, the avatar is also pulled across. The user's Elgg profile is sync'ed with their Facebook account. Users can unsync their profile from Facebook and fill in the Elgg one, if they want.

Issues:

• If Facebook goes down or they disable FBConnect, any users who have logged in using FBConnect will not be able to access their account on your Elgg site.
• It does not yet work with custom profiles, only the default Elgg one.

To use:

• Upzip and add to your mod directory
• Enable the plugin
• You need to register your site as an app with Facebook - http://www.facebook.com/developers/createapp.php - to obtain a key and secret
• Once you have created your app, under 'connect' you need to enter a Connect URL (route-to-your-elgg/mod/fconnect/) and Account preview UR
• You should also have cron running to enable synchronisation with facebook as well. 

  You can set cron up in you CPanel from the cron icon using:

  wget --output-document=/dev/null http://yourdomain.com/pg/cron/hourly

  and you'll be set up.  

  (change the yourdomain.com for youe domain name of course!)

nb...  Daemonik was banging his head against the wall trying to figure out where the Connect URL field is.  Apparently it is under the "Web Site" tab under Edit Settings and just says Site URL, now.