I use Live Id and Google as IP addresses, but I don’t know how to make the logout button.
From http://acs.codeplex.com/SourceControl/changeset/view/60691#1067602 :
WSFederationAuthenticationModule fam = FederatedAuthentication.WSFederationAuthenticationModule; try { FormsAuthentication.SignOut(); } finally { fam.SignOut(true); }