Google Earth replacement
Marble (http://en.wikipedia.org/wiki/Marble_(KDE), http://edu.kde.org/marble) should fulfill your need for a free Google Earth replacement. I'm actually surprised that the editor of your high priority list wasn't aware of this application.
I just saw on your high priority list that you're looking for a Google Earth replacement. We currently develop a landscape visualization system that handles planet sized terrains, called Biosphere3D:
- It is already open source under the MPL. Up to now, no external contributions have been made, so this is negotiable.
- It is based exclusively on open source libraries.
- It sports a state-of-the-art terrain management and rendering system. Our research has been published on the EuroVis and the SimVis conference, see http://www.zib.de/clasen/?page_id=4 .
- It handles large satellite images and digital elevation models, tested up to 2TB uncompressed (27GB compressed).
- There's already basic support for GIS data (shape file overlay).
- It's available for Windows (32 and 64 bit). The build system, the libraries and most of the code is already posix compatible, but we're lacking someone with proper experience in this field.
You can have a look at some screenshots at http://www.zib.de/clasen/?p=30 and http://www.zib.de/visual/projects/silvisio/silvisiolong.en.html . The source code is available via https://svn.zib.de/lenne3d/. The official project site (still somewhat empty) is http://www.biosphere3d.org/ .
Right now, only a single person (myself) is working on Biosphere3D, and the focus is vegetation rendering, not replacing Google Earth. However, I'd say that Biosphere3D has what it takes to become a Google Earth competitor, given that a few more people work on it. Please let me know if you're interested.
ossimPlanet
http://www.ossim.org is an open source project that provides an alternative to Google Earth. ossimPlanet builds on top of OSSIM and OpenSceneGraph to provide accurate 3D visualization of geospatial data sets. The project is LGPL and written in C++. The emphasis is on accuracy, collaboration through communications channel, and the ability to transform and project a wide range of geospatial formats to the planet on the fly. Basic support for KML and KMZ is in development. DTED, SRTM, and general raster elevation data sets are supported. Government and commercial geospatial formats are supported through internal file handlers and use of the GDAL plugin. Builds under gcc and is supported under Linux, Windows, and MacOSX.
