I would second this.
I tend to have a lot of location based notes and the ability to visualise these on a geographical map would be amazing.
As it stands I use Google My Maps to visualise locations but these are unconnected to my notes.
Tana, currently lets me effectively record and search for 4 out of 5 of the main query types but not location.
Who / What / Why - Dealt with via supertags for people, events, etc
When - Date Supertags
Where - Text only Supertag. A proper location tag would make this far more effective.
The same functionality could also be used to calculate people's ages if a date of birth was defined.