Sketchup file format
So apparently Google Sketchup uses Collada. A few programs can read its native format, but they haven't released any specifications. Any ideas on how you could read .skp files? Can you just use the DOM?
I remember asking on their forums about the Sketchup file format a year or so ago. Although there isn't a public spec, apparently if you were willing to sign some documents they would give you a C++ api for working with Sketchup documents, or something like that. So in theory I think you can write a Sketchup file reader, if you get their api. The DOM can't read Sketchup files.
Probably the best thing to do is write a Collada reader, and use Sketchup to export the Sketchup model as Google Earth kmz. If you unzip the kmz file there's a Collada file inside that contains all the model data. I think Sketchup Pro lets you export directly to Collada without going through kmz.