Sketchup doesn't officially run on Linux, but a group a avid Linux'ers have got it working under Whine. To read the file directly, you need the SDK. You can export from Sketchup to 3DS or FBX and probably work with those file formats under Linux, but, again, you need the Pro version to export to these formats, so again, you are hosed.
If you NEED it, then you NEED it, then spring for the $495 and get it.
Todd
