What Todd is flagging is an important issue - right now I have 3 different entries for Moscow, 3 for San Francisco, etc. Would be great to allow merging of the locations together, to display all of the contacts in those locations in a single list.

Yes please! I'd specifically love a way to merge and rename locations from the right panel on locations - as you can see, there end up being several different locations for Pittsburgh, San Fransisco, etc.

The thing I tried intuitively was to drag one location onto another - I'd expect dragging A onto B would show a prompt "Are you sure you want to change all contacts from location A to B"? or something similar. Another alternative would be like contacts where you have checkboxes that give you bulk edit options, including merge and delete (in this case, I'd expect delete to remove that location from the contacts, not delete the contacts - I might want to do that for garbage data from LinkedIn like "location = United States")