How do I limit panning in Google maps API V3?

I guess I’m a little bit late to the party, but since this was exactly what I needed just now AND I improved on it, I thought I’d post an answer anyway.

With both the answers of Daniel Vassallo and brendo, the user can still use the pan-control (if it’s activated) to move away from the wanted area. The thing @Yauhen.F mentioned in a comment.

So instead of using the dragend event, I use the center_changed event. This is continuously fired during dragging and every time someone uses the pan control.

// bounds of the desired area
var allowedBounds = new google.maps.LatLngBounds(
     new google.maps.LatLng(70.33956792419954, 178.01171875), 
     new google.maps.LatLng(83.86483689701898, -88.033203125)
);
var lastValidCenter = map.getCenter();

google.maps.event.addListener(map, 'center_changed', function() {
    if (allowedBounds.contains(map.getCenter())) {
        // still within valid bounds, so save the last valid position
        lastValidCenter = map.getCenter();
        return; 
    }

    // not valid anymore => return to last valid position
    map.panTo(lastValidCenter);
});

By saving the last valid position continuously during the dragging, the movement will just stop once it’s out of bounds, instead of yerking back once the dragging ended.
……