A new version of ArcGIS Explorer Desktop (build 1750) has just been released. See the ArcGIS Explorer blog for more information.
Check these locations to download the latest version:
ArcGIS Explorer Desktop is a free, downloadable GIS viewer that provides an easy way to explore, visualize, share, and present geographic information. The latest release of ArcGIS Explorer Desktop (build 1750) delivers fixes and improvements to the previous release. See this previous blog post for a list of new features and capabilities introduced with Explorer 1700.