I'm happy to report that now we have an osX native way to add GPS data to the EXIF data of our photos.
This new app has clean interface and does just what it says.
If you use it please donate to the developer. There are many other features that could be added on. I'm sure the developer will apprecate the support to know that others are using and value his software.
As the website mentions, you should consider backing up your photos before using this. It is unlikley but possible that a jpg file could become corrupted in this early version of the software.
Once the files are tagged with the GPS data, if you open it in browser such as iView you can now see the Latitude and Longitude fields.
What is left now is to automate the process of creating an image map to view the photos. This may come from the maker of GPSPhotoLinker or maybe somewhere else. I am aware of at least one other osX app that can automatically generate image map to view photos as pins on a map. It just does not use GPS data; instead it relys on hand placing pins. I have asked that developer about adding the abilyt to use GPS data form EXIF.