After hammering at this (along with some other projects) for a couple of weeks I've determined that FileCutter cannot be reimplemented using Snow Leopard's "replacement" for the context menu plugin mechanism. I will be making available for registered users a package that restores a small subset of FC's functionality under 10.6. I think it will still be useful. But please do not register FileCutter if you have Snow Leopard or expect to upgrade in the near future.