I have no personal experience and even less direct knowledge but since no one else is adding to this thread I thought I'd share what I know with you.
What normally happens is that the phone, tablet or computer has software that can receive the lat/long data from a GPS. The GPS can be built into the device or connected to it through a cable or bluetooth. The software on the device then uses the lat/long it got from the GPS to find the location of the lat/lon on a map which it then displays. The map can be stored on the device like many driving direction GPS units or can be downloaded from the Internet using a wired, WIFI or a cellular phone connection like Google Map.
So our first problem is that the ex124g doesn't have an internal GPS that is found in almost all smart phones and many regular phones. This mean that it can't automatically tell the software were it's at. This doesn't mean it can't be used at all, you can after all just tell it were you are by entering your address for example and the software will then download the map. There are people on this forum reporting success with using Google map on the ex124g doing exactly this. There are also people on this forum reporting being less than thrilled with the results. I think it may depend on what your needs are and the accuracy of the maps in your area. Notice if you know were you're at and the address of the place you want to go then you can get turn by turn directions by going on line with your phone and you don't need fancy software and GPS units. That may under certain circumstances be very useful.
There is another point of interest here as well. I have for many years been using a DELL Axim at work as a field mapping tool by using the Axims bluetooth to connect to an external GPS unit. I think it would be very interesting to see if the ex124g can connect with a bluetooth GPS by way of it's bluetooth transmitter. If that is possible then maybe software like Google Map can track your location on a map in real time.