Anyone know if there's a way to have FCP increment a sequential number when doing a "save as"; at the moment, it just seems to suggest appending "copy" to the saved project, which I don't find useful.

Not quite what your looking for but...

Under Final Cut Pro>User Preferences>General Tab, you can set the AutoSave Vault to save every 10 minutes or whatever. This will save an incremental copy of your project with a sequential number assigned to each time it Auto Saves. But be careful, I "think" that when you manually save it deletes all the auto-saved project files. This is really easy to test and figure out exactly how it works. Give it a try. It works.

Thanks Mitchell, appreciated -I'll check this out.

Costs a bit, but still less lost time and work:
FCP Versioner - Version Control for Final Cut Pro (http://www.digitalrebellion.com/fcp_versioner.htm)

Hope something similar will come out for Color since autosave overwrites the original. Very annoying if undo is not possible (after a huge mistake, just a second before autosave...)