It's not a loophole. It's a basic freedom of software development
under the GPL: the right to privacy. You have the right to make
private enhancements without being forced to distribute. No one
would ever take the risk of enhancing OpenACS if they found
themselves forced to contribute *all* future enhancements to the
public.
If you do distribute, however, then you must respect the rights of
the original developers and release your enhancements in the
same way the original developers provided you with the original
code.
