Open source for wordpress plugin smf2wp 2 years ago, I wrote this plugin for my community site. However I don't have enough time to maintaince this plugin. I would appriciate if somebody continue the work with me.
Feel free to edit and ask for a pull request.
Plugin website: http://wordpress.org/extend/plugins/smf2wp/
You can use global variable $smf_user_info['smf_groups'] to see which groups the users belongs on the SMF side