you can set them invisible by setting the map style properly. See
http://code.google.com/apis/maps/documentation/javascript/styling.html
and
http://code.google.com/intl/pl/apis/maps/documentation/javascript/reference.html#MapTypeStyleFeatureType
sth like that should do the trick (though not tested):
var noPoi = [
{
featureType: "poi",
stylers: [
{ visibility: "off" }
]
}
];
map.setOptions({styles: noPoi});