The following code works great on a Motorola Defy with Android 2.3.3 However it's not working on a Nexus 4. The LED itself should be fine, the app color led tester from the market works.
NotificationManager notif = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
final Notification notification = new Notification();
notification.ledARGB = Color.RED;
notification.ledOnMS = 1000;
notification.ledOffMS = 300;
notification.flags |= Notification.FLAG_SHOW_LIGHTS;
notif.notify(1, notification);
Does anybody know what will do the trick here?