You can import UserName, FirstName, LastName and Email. Where FirstName + LastName becomes FullName for BuddyPress.
This plugin will automatically activate all user accounts and send notification as selected by the admin at the time of import .
It currently works with WordPressMU + BuddyPress installation.
If you have any issue with this plugin, need help, or have any suggestions, You may contact me at http://manojkumar.org or www.futurescape.in.