I made some *vast* improvements to the comments system with the Simple Facebook Connect plugin.
Comment emails: If you have the “Comment author must fill out name and e-mail” checked in Settings->Discussion, the comments plugin will now ask the Facebook user for Permission to email that user. This will allow things like replying to the comment emails and Subscribe to Comments and similar plugins to work with Simple Facebook Connect. Yes, you can actually reply to the Facebook comments when the comment from WordPress gets emailed to you, and the reply *works* and sends back to the comment author through Facebook. Tested, proven.
The Comments plugin now uses the comment meta table for storing FB user id, making for *much* quicker avatar generation. Avatars used to be built by getting FB UID from the email field, which took time for regex parsing. Old avatars will be auto-converted to new method when displayed. This also has an advantage in that there’s now an ‘fbuid’ comment meta field on every facebook connected comment, to tie back to the author of the comment.
On the whole, I think it works better, but since it’s really beta, I’ve also split the plugin into tagged versioning. I’d like some testers to help me out and find bugs, actually.
The current stable version is 0.9 and lacks these new comments enhancements, but if you want to use the latest trunk code, you can get that trunk code via SVN here: http://plugins.svn.wordpress.org/simple-facebook-connect/trunk/