There has been some interesting discussion of Anselm's 'ontological argument' lately. See
Anselm, Kant, and What to Do with the Ontological Argument at "Per Caritatem";
Is Anselm's Ontological Argument Ontological? at "Sacramentum Vitae"; and
Jottings on the So-Called Ontological Argument at "Assimilatio Dei". I've
posted on the argument before; I'll only reiterate my recommendation of
Gyula Klima's writings on the subject, as well as the papers of Millican and King that recommended
here.