They can be exported as rasters via the standard formats such as GIF, PNG, JPG and therefore can be used in many other applications. Go to the fireworks symbols panel and place a symbol on the document / page and then go to the file menu save command
The save as command exports them to PNG, BMP, GIF, PSD, TIFF etc. If you want to export the images as vectors for use in Adobe ® Photoshop ®, such as using the Fireworks shapes as vectors then you can use the PSD format. Export the shapes via the PSD format with editability on, also the shapes etc must be on individual layers (and not on the same layer). Open Photoshop and then open the PSD and use the vector shape layers (you can also even used the export artworks as Photoshop custom shapes). If you export the shapes in PNG and other formats the artworks are stored as raster format files, if you re-input them into FW the image will still be raster. The vector information has been lost. To export& save Fireworks symbols to a vector format then the best format is probably AI as you can use the exported Fireworks symbols (as well as auto shapes) as vectors in Adobe AI and these can be exported to other applications. The save command (different from save to) only saves PNG. Export shapes for use in Adobe ® Photoshop ® [Youtube] / Export auto shapes for use in Adobe AI etc [Youtube]
Or use the export wizard as this offers a selection of options such as GIF, animated GIF, JPG, TIFF. The export command offers a suggestion (such as TIFF) but you can always override this once you get to the end screen for the export.
The export command with CS6 offers only PNG (which is a useful format for transferring assets) for raster format and PDF and a few others. I have to say the PDF on the surface for the export of Fireworks symbols seems a great idea, the results end up as raster as well (in tests) which does negate the use of PDF. So ultimately, AI format seems about the best choice for export of shapes and that is in the save as menu.
You may find the Fireworks symbols of interest