New Natural Earth 1.4.0 Data Added to MapBox GeoData Library for TileMill
The most noticeable change is that South Sudan had been given official independent status. There are numerous other improvements and corrections - see the Natural Earth blog for a fully-detailed changelog.
The 1.4.0 release has not replaced 1.3.0 in the MapBox library, but sits alongside it. The new files are available in new and existing installations of TileMill (version 0.4.0 or later), which is available for free download at TileMill.com.