I too saw the http://www.geocaching.com/seek/gmnearest.aspx, which is a nice implementation. However, it isn't optimized for the mobile browsing. If that implementation could be optimized for mobile browsing, that would be great.
I have been experimenting with converting pocket queries into contacts and then syncing them with the iPhone. I'm really not looking for the iPhone to replace my GPSr. I just want to be able access the cache details and record my success and failures with it, especially if I am out of range.
After some monkeying around, I moved the coordinates from the Organization field to a Address field. This allows me to open the address with the Google Maps widget. However, Google doesn't like coordinates with a country and returns a negative search result, but if you delete the country manually, it pops up in the Google Maps widget.
More observations to follow . . .