To be explicit, this is when google adds an outline relating to the search query. If you were to search for a town, a post code, or a zip code, Google will highlight this region of the map. Example:
This was apparently not available via the API, and only through Google's own web properties.
Recently, I noticed some other domains using this functionality, for example on Twitter.
Is there a seperate API Twitter and other large organisations are using? Has this functionality been added, but is as yet undocumented? Or have I simply missed the announcement and can't find any docs?