Hello,
This is a bug report and feature request at the same time!
I use easy profile and I also use CMC Mailchimp from http://compojoom.com Part of that extension is to allow a tick box into the registration form for people to sign up to the newsletter. If I enable this plugin with easy-profile system and user plugins enabled, it doesn't show. Turn them off and it works fine. So some kind of conflict I guess.
So, for the feature request, how about adding in mailchimp integration during registration and when logging on via social network? Not sure how complex that would be to do?
thanks Pete