Hide groups based on role - using a busniess rule: before ---- query --- http://wiki.servicenow.com/index.php?title=Hiding_Groups#gsc.tab=0
if (!gs.hasRole("admin") && !gs.hasRole("groups_admin") && gs.getSession().isInteractive()) {
var qc = current.addQuery("u_hidden", "!=", "true"); //cannot see hidden groups...
qc.addOrCondition("sys_id", "javascript:getMyGroups()"); //...unless in the hidden group
}