It appears that another round of scam threatening letters is going around regarding employment posters. These letters look very "official" and threaten the church with dire consequences if you don't buy their posters.
Churches are not exempt from posting requirements, but ALL the posters you need are available for FREE download from the Illinois Department of Labor. Because different churches are in different circumstances, which ones to post vary from church to church. If you are in doubt, post them all. There is no penalty for posting something that you didn't have to. The website follows and there is even a link for the Federal posters: http://www.illinois.gov/idol/Employers/Pages/posters.aspx