When I have several images geotagged then open the map window and preview window and move between pics, the preview window shows the next pic, but the map window does not show the next location. Maybe it is showing my current location. Having then both move along would be handy for fine tuning your locations.
And when it comes to fine tuning pic locations another nice feature to add would be the ability to make small time nudges (to all the pics simultaneously). That way you can be looking at one certain photo in the preview window, its location in the map window and make several one or two second nudges until the location is spot on. All of your other pics should have their location updated at the same time automatically. I realize that you can do this as you load your photos, but it would be nice to be able to fine tune as well. I take many photos as I'm driving and even if I make the proper time correction when loading the images, I'm not totally satisfied with the location. They still look a couple of seconds off. Maybe I drive too fast!!!
I've looked at the instruction manual for Aperture 3 (don't want to pop the $199) and here's how you use a GPX tack. You download the track from your GPS and it shows up on a map. Then you drag one of your images that you know the location of - like an intersection onto the track and drop it at its exact location. Then you drag all the other photos onto the map as a group and they snap to their proper location. What I don't know is if you can move that key photo after the fact and have all the other photos automatically march along the track together.