Running on OS X 10.9 this simple code I'm getting null instead of PrintService:

import java.applet.*;
import javax.print.*;
import javax.print.attribute.*;
import javax.print.attribute.standard.*;
public class PrSrvApp extends Applet {
    public void start() {
        setSize(200, 200);
        setVisible(true);

        System.out.println("service:"+(PrintServiceLookup.lookupDefaultPrintService()));
    }
    public static void main(String args[]) {
        PrSrvApp app = new PrSrvApp();
        app.start();
    }
}

Reproducible with jdk9 b03 promoted build on OS X 10.9 and not on Linux.

Not reproducible with b02 and with the first client PIT, so it is some strange regression introduced even before any recent client code found a way to the master.

 lpstat -v reports:

device for spb04p21: lpd://10.162.80.34
device for Xerox-WorkCentre-35-by4015: socket://10.162.84.33:9100
device for XRX0000AACE62DD_local_: dnssd://XEROX%20WorkCentre%204250%20(Spb04p02)._printer._tcp.local./

Last printer listed is a default one. It is reported by lpstat -d as
system default destination: XRX0000AACE62DD_local_
and by older java builds as
IPP printer : Xerox WorkCentre 35

A driver is a newest available Xerox driver for OS X.