With the note that you can be as vague as putting in your country, or as precise as putting in your address--whatever you're comfortable with. The map will handle cities, zip codes, states, maybe provinces and the like. Don't want to make anyone feel we're prying.
I think it's a lovely idea to encourage people to just say hi occasionally and I, as one with freaky privacy issues, dig that it can be as vague or precise as people are comfortable disclosing.