No, when I say Geoformat I mean the microformat geoformat.
The Template:GeoGroup makes use of it. And the Template:Coord too I guess.
Operator in action: install it and go to https://en.wikipedia.org/wiki/Template:GeoGroup,
As you see Operator detects the semantic of the geoformat and proposes actions relative to that.
Let's have a look at the source of the first item:
<td>Dudley Port Junction</td>
<td>(...)
<span class="geo-nondefault">
<span class="geo-dms" title="Maps, aerial photos, and other data for this location">
<span class="latitude">52°31′19″N</span>
<span class="longitude">2°02′36″W</span>
</span>
</span>
</td>
If you're speaking about an article written on "our" Wiki, you're right, we can probably make use of existing templates like this one. I was referring to article written in html and then a way to create a template.
So the answer to your proposed structured coordinate format has a name: geoformat microformat. See it in action: http://microformats.org/wiki/geo-examples-in-wild-fr).
But if you want to see Wikipedia articles on a map, I've a better solution as not all articles in Wikipedia have the right template, you can do it the other way round, extracting data from OpenStreetMap (their - our ;-) - database is rich of links to Wikipedia articles). I'll answer to this comment with an example.