LinkedIn is working on a new feature for groups: Open Groups.  With this feature, the discussions in an open group can be shared via Twitter and Facebook.  Additionally, they will be indexed by search engines.  What a viral power this will give to a simple discussion in LinkedIn!  The main benefit is that you, the LinkedIn user, can view and participate in discussions without being a member of the group.  So, let’s say you are a coach and you are interested in career coaching.  With the open group feature, you can go into any group and post a discussion or participate in a discussion that would interest you.  If the discussions are indexed by the search engines, you will be able to find interesting discussions through the search engines as well.  This means, that you can look for interesting discussions for your field of expertise and participate in them.  I really like that.

For those of you, who do not like to share their discussions with the web (and missing a great opportunity to spread the word), LinkedIn says that “all existing groups will remain members-only unless the group owner proactively chooses to enable public discussions. If that happens, all group members will be informed when they visit the group. Discussions created in a group before it switches to open will go into the group’s members-only, read-only Archive. They cannot be seen by anyone who is not a member of the group.”  So, you have nothing to worry about. 

Source: http://help.linkedin.com/app/answers/detail/a_id/4780