In v3 this has changed a bit. Check out the documentation at http://code.google.com/apis/maps/documentation/javascript/reference.html#StreetViewService
The updated code is:
var streetViewService = new google.maps.StreetViewService();
var STREETVIEW_MAX_DISTANCE = 100;
var latLng = new google.maps.LatLng(40.7140, -74.0062);
streetViewService.getPanoramaByLocation(latLng, STREETVIEW_MAX_DISTANCE, function (streetViewPanoramaData, status) {
if (status === google.maps.StreetViewStatus.OK) {
// ok
} else {
// no street view available in this range, or some error occurred
}
});