I hope you don't mind that I share the answer with the list. I think the answer to this question might be of general interest.
the JavaScript creating the visualization in the browser is here:
As you can see it is just a simple usage of HTML5 canvas.
It requires two data files as these (careful, large):
The first contains all items, their latlong, and their label.
The second contains the graph, the way items are connected to each other.
The latter two files are created by the following Python scripts, in two steps. First, you need to create the knowledge base. This can be done with the following scripts:
Use there the script
Careful when you run it, it will download all Wikidata dumps. This might need a few free Gigabyte and a decent internet connection.
Now, you should have the file kb.txt.gz, containing the knowledge base.
By the way, you can also download the knowledge base as it is created nightly by us here:
Finally, you will need a few scripts from here:
Run them in the following order:
This should you give the two files wdlabel.js and graph.js, which will be called by the Wikidata Map Interface (see it's HTML source in order to see how).
This process is run nightly on a machine we have standing here in the office. I am planning to set this up on labs, but didn't find the time yet.
I hope this helps,
Denny