As James Fee noted, a new version of ESRI ArcGIS Explorer Beta is available — build 350, up from build 348. As detailed by the changelog, new in this version are options to use the MGRS and US National Grid coordinate systems:

Preferences for clouds and lighting have been moved from the “Options” pane to a “Map Properties” pane, and these settings are now saved with each globe’s .NMF file, rather than with the application.

You can now also paste a URL link to a KML file to add it to ArcGIS Explorer, though KML support doesn’t appear to have improved — you still can’t see pop-up windows for placemarks, for example.

Otherwise, the criticisms from last week’s review have yet to be remedied — zooming to a placemark still avoids the dateline, the default cloud view is a placeholder, and imagery, labels and borders download slowly.