gcg co-ordinates to GPS co-ordinates

When I create a view and add the gcg_longitude and gcg_latitude and set the display to "coordinates" it displays it in this format:

-23.567994 and 08.34575

but if you load these coordinates to your GPS unit it is +/-21Km off

I understand this has something to do with the [datum] lines.

Is there a way to fix this?

More and more people have GPS units and introduction of GPS to mobile phones is making it even more popular.
Enabling people to copy coordinates to there GPS device will give this module an added feature.

Or is this more a gmap.module issue, or should this be a module on its own, so that it can work with other geo modules?

Thanks for the great work, this module is excellent.