Why is my CLLocationmanager delegate not getting called?

I'm not getting any location callbacks on either sim or device. I've got this code being called:

- (void)startLocationCallbacks: (NSObject*) ignore
{
  locationManager.delegate = self;
  locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
  locationManager.distanceFilter = MINIMUM_METERS;

  [locationManager startUpdatingLocation];
  NSLog(@"[DEBUG] [locationManager startUpdatingLocation] (%@, %@)", locationManager, locationManager.delegate);
}

and log statements at the top of both

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error

and

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation

but neither log statement ever gets called. Location Notifications are enabled for my app (as shown in Settings, plus I said "allow.")

What are some possible reasons that I'm not getting location updates?

Config/other info:

• I have allocated locationManager, and saved it in a retain property.
• I have called startUpdatingLocation
• I'm using 4.1 SDK
• Problem is on both Sim & iPod-touch (2nd Gen) & iPhone-3, all running 4.1
• Location notifications are allowed in my app (both as indicated in Settings and because I clicked "allow" in the alert.)
• I've used CLLocationManager successfully before (in many shipping apps!) This is a real hair-puller for me.

Thanks!