Have you ever wondered why LinkedIn has a "Jobs" tab on the main menu and a "Jobs" and sub "Job Discussions" feature in groups? "Jobs" on the main menu are paid job posts by companies that are searchable by any LinkedIn user.LinkedIn magically knows which jobs to post in the group by keywords and geographic location of the group and job.
To view jobs posted by LinkedIn members to a group, you have to visit the group and click on the group jobs tab and then 'Job Discussions'. These jobs are not searchable outside of the group (unless the company ponied up and purchased a job post from LinkedIn).
This is the beauty and power of groups and connections and one of the reasons I haven't used paid job postings in 6 years to source candidates. Using 2.0 tools the right way allows me to keep my costs down for companies that contract with me for talent acquisition services and to meet service level agreements fast and furious.
So whether you are a recruiter or job seeker (passive or active) - next time you visit on of those 50 free groups LinkedIn allows you to join, click on the group jobs tab to see what's going on. Recruiters have an extra quiver in their toolkit where they can post a small intro and the link to the job posting/apply link and job seekers have the advantage of already being connected to the recruiter through the group.
It doesn't get much better than that.