Just learn about two mobile functions:
Location returns the current latitude and longitude.
LocationValues can get more detailed info.
If you are using FileMaker Go 12 you can use the new Location functions; Location or LocationValues. Both of these are outlined in FileMaker 12 Help.
If you are using the older version of FileMaker Go, you will need to do this using a web page. I seem to remember that there was an issue with getting the location data in a web viewer, so you need to actually go out to the page and then return the geolocation data back to FileMaker using the FMP7Script protocol.
You will need to replace the variable with your values. Unless I have got something wrong that code will run the specified FileMaker script with the variables $Lat and $Long
thanks for that information - it answers my question completely in two different ways! I was using FM 11 and missing the built in functions for getting location data. I think I'll update to 12 to make this a simpler task.