BuddyPress.org

It’s just a start, but after I heard the news about Ning I wrote a plugin that will import users from Ning to WordPress: http://teleogistic.net/2010/04/importing-ning-users-into-wp/.

Sadly Ning doesn’t offer easy export of the rest of the content. But I think some folks out there are working on ways for you to get your forums, discussions, blog posts, etc out of there as well.