There is somewhat of an announcement on the ArcGIS Explorer Blog about the next release of ArcGIS Explorer.
In the Showcase and at the sessions we were using both the currently available public download (Build 380) and also showing one of the more recent software builds (Build 392) to highlight some of the new features that you can look forward to in the next release. This upcoming release of Explorer will continue to evolve for a few more weeks and will be delivered sometime in July.
Not much there, but I assume some better KML support (2.0/2.1?) and maybe some increase in speed. I’d love to roll out some AGX applications internally at my company, but I’m sticking with the .NET Web ADF for now.
** Mechagodzilla is better than old AGX Godzilla **