To elaborate on your question, when one selects a graphic in ChemDraw and uses the right click menu to copy it, the format is apparently Microsoft Imaging Document format (.mdi) which is based on .tiff. I thought that OpenOffice could handle .tiff, but it doesn't seem to work as yet. I'm using the OOo binaries, so I might benefit from compiling from source and including .tiff support, but that's a loooong painful compile. Do you know if .mdi contains extensions that are incompatible with the .tiff libraries available for linux?
In the case of actually embedding ChemDraw objects inside of word processing documents, I've found that even on a fast, up-to-date windows machine, embedding ChemDraw objects into Word documents often leads to file corruption and lots of headaches. I avoid the problem by inserting as images the files (.png or .tiff) that I "save as" in ChemDraw. For those of you about to murder your computer because your 150 page thesis keeps crashing with ChemDraw errors, stick with images. I know it's more burdensome than embedding the object and being able to edit it just by double clicking, but you'll save yourself a world of hurt going with images.
-Tom