The documentation for Google Maps for iOS states that:
Call one of several methods that allow you to animate the camera moving to a new location. You can
I found the answer ... you can control the animation duration by wrapping one of the animate* methods in a CATransaction, like this:
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat: 1.0f] forKey:kCATransactionAnimationDuration];
// change the camera, set the zoom, whatever. Just make sure to call the animate* method.
[self.mapView animateToCameraPosition: [self newCamera]];
[CATransaction commit];