Copyright is a complex issue. As a general rule facts (John Jones was born in 1851) are not copyrightable, but the presentation of those facts is. In other words posting verbatim excerpts from books, cds, etc. to the list is copyright infringement. In addition many Irish Parish Registers are Church property, and the Church does not want them published. While you may not agree with this, you must respect their wishes. The best advice I can give is "When in doubt, ask permission first."
A site on international copyright agreements