I also tried some. Blender can import a kmz with
this plugin and save it, for instance, as 3D Studio file. That file is able to be opened by SU.
But may create problems in details; I am not sure. I didnt try it with textures, either.
'Google SketchUp' has a file in 'Importers' folder named "KMLImporterLibrary.dll".

Weird.
Kass, why dont you find the plugin (or the right file) that imports kml and try to amend it to the new SU version? May work...