The image of the week is a screenshot of an OSM editing program,
Mapzen. http://maps.cloudmade.com/
About Image of the Week
These are Featured images, which have been identified as the best
examples of OpenStreetMap mapping, or as useful illustrations of the
OpenStreetMap project.
If you know another image of similar quality, you can nominate it on
Featured image proposals.
http://wiki.openstreetmap.org/wiki/Featured_image_proposals
It is not Mapzen, it is Cloudmade maps interface with form for logging in to Mapzen.