I've been having the same problem-- works in the morning, stops working at night.
Here's my theory. We know that Google throttles reverse-geocoding requests by IP. My suspicion is that this throttling is reset at midnight each night and that MKReverseGeocoder passes its requests through a centralized caching proxy; since that proxy would appear as a single IP to Google, it stops working at a certain point during the day.
In any case, I ripped MKReverseGeocoder out of my app and rolled my own custom class using Google's new REST API (
Geocoding - Google Maps API Services - Google Code) , and the app has been working great.
Hope this helps. The other thing someone could do is to try complaining to Apple and/or Google and get them to fix this, but rolling my own was easy enough and I didn't want to wade through the support bureaucracy.
