There's no killer reasoning behind using an image for maps. We could be using the Google Maps API instead though right now it lets you share the actual image. We don't consider the maps to be overly important.
When people start using it to broadcast events like accidents, fires, etc., you're going to want to use URLs, not pics.
If they've just seen an accident, they'll want to post a URL. If they're at home, not likely.
You might even ask users to "mark" private locations from which location can't be sent, like school, home, or work.
You could also allow the user to vary the accuracy of the position by zooming in/out, to give them control of proximity for their posted locations.