There's no criteria that I'm aware of in iPhoto to do what I think you want to do (which is to delete the "photo" (really a reference to it) from iPhoto and have it moved to the trash from its original location as well. What iPhoto does in that circumstance is more like unimporting. You can use the command to reveal it in the Finder, but there isn't an automatic way to do do this in batches.
iPhoto is non-destructive to a fault in this instance.
If this is the sort of thing you wish to do, Aperture or Lightroom would be a better choice. Perhaps you could download a test copy of LR 4 and see if it accomplishes what you wish; I think you can import the references from iPhoto (not sure though).
Unfortunately iPhoto doesn't offer much control when importing either; otherwise you could attach a tag or other criteria so you could use an external search to find the originals to delete them.
It does seem like the iPhoto database would keep the path names of the originals; maybe there's a way to tease that out somehow. Would be useful.
