I have spent quite a bit of time developing IDL code in the past, and it appears I will do some more in the near-term future. I have decided to release my IDL code library to the public so that others can perhaps benefit from my work. This is a work-in-progress and access is via Subversion.
One subset of the library is the KDM_KML lib for writing KML files. This code should make it fairly simple to display data sets in Google Earth from IDL.
I have currently implemented about 50% of the KML API and will get the rest implemented as time goes on. Right now layers can have overlays, points (placemarks), or linestrings (paths). Any element (that the API supports) can have a timestamp, and styles are supported too. With knowledge of the KML API you can create artistic balloons with whatever content you like that can even link to each other.