We have already the
<time> element which is quite useful. We could have a
<geo> element. for marking places.
<p><q cite="urn:isbn:978-0684824994">If you are lucky enough to have lived in <geo geolocation="48.856667, 2.350929">Paris</geo> as a young man, then wherever you go for the rest of your life, it stays with you, for Paris is a moveable feast.</q> once said Ernest Hemingway in <cite>A Moveable Feast.</cite></p>
The model of values could be declined through similar constructs than the time element.
<geo geolocation="48.856667, 2.350929">Paris</geo>
The browser would create a Coordinates object.
Why it could be useful?
It could enable application where you might want to show a map widget for localizing a place you are mentioning in a text, such as an hotel page.
You might want to be able to automatically extract geodata from a document without relying on complicated heuristic or ambiguities, such as Paris in France or Paris in Texas.
As I'm pretty sure this is not a new proposal, there are certainly plenty of discussions already on W3C mailing-lists to dig out.