Question: Is there a way to call an external script or program from Flash CS3 every time it builds a SWF file? I'd like to add subversion information using subwcrev - the SVN keywords don't work because they only update when the version class file is updated.

Answer: 
I'm not sure what are JSFL capabilities these days, but I'd say inside Flash IDE is your only bet. JSFL is a language to extend the Flash IDE, but I'm not sure you can do this.

On a related note, adding SVN information to your SWFs is not trivial. You'd probably need SVN hooks to put the information *before* actually compiling the SWF itself. 

I doubt you can do this compiling with Flash IDE but I'd be more than happy to hear otherwise.
lessen i do this 
may it's us full for you're too

var fileURL = fl.browseForFileURL("open", "Select file");

fl.openDocument(fileURL);

var documentDom = fl.getDocumentDOM();

documentDom.exportSWF("movie.swf",true);

documentDom.close(false);